Electronic image pickup system

ABSTRACT

The invention relates to an electronic image pickup system whose depth dimension is extremely reduced, taking advantage of an optical system type that can overcome conditions imposed on the movement, of a zooming movable lens group while high specifications and performance are kept. The electronic image pickup system comprises an optical path-bending zoom optical system comprising, in order from its object side, a 1-1st lens group G 1 - 1  comprising a negative lens group and a reflecting optical element P for bending an optical path, a 1-2nd lens group G 1 - 2  comprising one positive lens and a second lens group G 2  having positive refracting power. For zooming from the wide-angle end to the telephoto end, the second lens group G 2  moves only toward the object side. The electronic image pickup system also comprises an electronic image pickup device I located on the image side of the zoom optical system.

This application is a divisional of prior U.S. patent application Ser.No. 12/283,106 filed on Sep. 8, 2008, which is a divisional of U.S.patent application Ser. No. 10/142,219 filed on May 10, 2002, now U.S.Pat. No. 7,436,599 granted on Oct. 14, 2008, and also claims foreignpriority benefits under 35 U.S.C. §119 of Japanese Application No.2001-142948 filed on 14 May 2001, the contents of each of which areincorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates generally to a slim electronic imagepickup system comprising an optical path-bending zoom optical system,and particularly to an image pickup system inclusive of video cameras ordigital cameras, the depth dimension of which is reduced by contrivingan optical system portion thereof, e.g., a zoom lens.

In recent years, digital cameras (electronic cameras) have receivedattention as cameras of the next generation, an alternative tosilver-salt 35 mm-film (usually called Leica format) cameras. Currentlyavailable digital cameras are broken down into some categories in wideranges from the high-end type for commercial use to the portable low-endtype.

In view of the portable low-end type category in particular, the primaryobject of the present invention is to provide the technology forimplementing video or digital cameras whose depth dimension is reducedwhile ensuring high image quality.

The gravest bottleneck in making the depth dimension of cameras thin isthe thickness of an optical system, especially a zoom lens from thesurface located nearest to the object side to the image pickup plane. Tomake use of a collapsible lens mount that allows the optical system tobe taken out of a camera body for phototaking and received therein forcarrying now becomes mainstream. However, the thickness of an opticalsystem received in a collapsible lens mount varies largely with the lenstype or filter used. Especially in the case of a so-called + precedenttype zoom lens wherein a lens group having positive refracting power ispositioned nearest to its object side, the thickness of each lenselement and dead space are too large to set such requirements as zoomratios and F-numbers at high values; in other words, the optical systemdoes not become slime as expected, even upon received in the lens mount(JP-A 11-258507). A − precedent type zoom lens, especially of two orthree-group construction is advantageous in this regard. However, thistype zoom lens, too, does not become slim upon received in a collapsiblelens mount, even when the lens positioned nearest to the object side isformed of a positive lens (JP-A 11-52246), because the lens groups arecomposed of an increased number of lens elements, and the thickness oflens elements is large.

Among zoom lenses known so far in the art, those set forth typically inJP-A's 11-194274, 11-287953 and 2000-9997 are suitable for use withelectronic image pickup systems with improved image-formationcapabilities including zoom ratios, field angles and F-numbers, and maypossibly be reduced in thickness upon received in collapsible lensmounts.

To make the first lens group thin, it is preferable to make the entrancepupil position shallow; however, the magnification of the second lensgroup must be increased to this end. For this reason, some considerableload is applied on the second lens group. Thus, it is not only difficultto make the second lens group itself thin but it is also difficult tomake correction for aberrations. In addition, the influence ofproduction errors grows. Thickness and size reductions may be achievedby making the size of an image pickup device small. To ensure the samenumber of pixels, however, the pixel pitch must be diminished andinsufficient sensitivity must be covered by the optical system. The samegoes true for the influence of diffraction.

To obtain a camera body whose depth dimension is reduced, a rearfocusing mode wherein the rear lens group is moved for focusing iseffective in view of the layout of an associated driving system. It isthen required to single out an optical system less susceptible toaberration fluctuations upon rear focusing. Alternatively, suchthickness reductions may be achieved by bending the optical path of anoptical system with a mirror or the like; however, some considerablerestrictions are imposed on the zooming movement of lenses because ofthe space for such optical path bending.

SUMMARY OF THE INVENTION

In view of such problems with the prior art as referred to above, theprimary object of the present invention is to provide an electronicimage pickup system with extremely diminished depth dimension, whichmakes use of a rear focus type zoom lens wherein the optical path(optical axis) of an optical system is bent with a reflecting opticalelement such as a mirror, and restrictive conditions for the zoomingmovement of a moving lens group can be substantially eliminated whilemaintaining high specification requirements and improved performance.

According to the present invention, the aforesaid object is accomplishedby the provision of an electronic image pickup system, characterized bycomprising an optical path-bending zoom optical system comprising atleast one lens group that moves only toward an object side of saidoptical system for zooming from a wide-angle end to a telephoto end ofsaid optical system and at least one reflecting optical element forbending an optical path, which element is located between said objectside of said optical system and a lens included in all lens groupsmovable during zooming and located nearest to said object side of saidoptical system, and an electronic image pickup device disposed on animage side of said optical system.

Why the aforesaid arrangement is used in the present invention, and howit works is now explained.

In the present invention, there is used an optical path-bending zoomoptical system comprising at least one lens group that moves only towardthe object side of said optical system for zooming from a wide-angle endto a telephoto end of said optical system and at least one reflectingoptical element for bending an optical path, which element is locatedbetween said object side of said optical system and a lens included inall lens groups movable during zooming and located nearest to saidobject side of said optical system. To direct the entrance surface ofthe lens system toward the object side and reduce the depth dimensionthereof, it is preferable that the optical path is bent at a position ofa phototaking optical system which is as close to the object side aspossible and at an air separation where the height of light rays is low.To simplify the driving system for zooming and focusing purposes, themoving lens group(s) is preferably located at an image side positionwith respect to the bending position. To reduce bending space as much aspossible, it is preferable that the composite or combined focal lengthof a partial system from the lens disposed nearest to the object side,at which the bending portion exists, to just before the lens group thatmoves during zooming, is negative, because the heights of all light rayscontributing to the formation of images in the vicinity of the bendingposition should preferably be low.

Specifically, one lens arrangement well fit for the bending zoom opticalsystem is of the type that comprises, in order from its object side, a1-1st lens group comprising a negative lens group and a reflectingoptical element for bending an optical path, a 1-2nd lens groupcomprising one positive lens and a second lens group having positiverefracting power, wherein for zooming from the wide-angle end to thetelephoto end of the arrangement, the second lens group moves onlytoward the object side of the arrangement.

Another lens arrangement well suitable for the bending zoom opticalsystem is of the type that comprises, in order from its object side, a1-1st lens group comprising a prism that is a reflecting optical elementfor bending an optical path, wherein at least one of an entrance surfaceand an exit surface is defined by a concave surface, a 1-2nd lens groupcomprising one positive lens and a second lens group having positiverefracting power, wherein for zooming form the wide-angle end to thetelephoto end of the arrangement, the second lens group movesmonotonously toward the object side of the arrangement.

In either type, it is preferable that an axial distance d, as calculatedon an air basis, from a refracting surface just before the reflectingsurface of the reflecting optical element to a refracting surface justafter the reflecting surface should satisfy the following condition (a):

0.5<d/L<2.1  (a)

where L is the diagonal length of an effective image pickup area (in asubstantially rectangular form) on the electronic image pickup device.

As the upper limit of 2.1 to this condition (a) is exceeded, the opticalsystem becomes too large. As the lower limit of 0.5 is not reached, alight beam that contributes to the imaging of the perimeter of an imagedoes not satisfactorily arrive at the image plane or ghosts are likelyto occur.

It is noted that when the field angle in the optical path-bendingdirection is in the range of 25°±3°, condition (a) should preferably bereduced down to the following condition (a-1), and when it is in therange of about 19°±3°, condition (a) should preferably be reduced downto the following condition (a-2).

0.8<d/L<1.9  (a-1)

0.5<d/L<1.5  (a-2)

More preferably,

0.9<d/L<1.8  (a′-1)

0.6<d/L<1.4  (a′-2)

In either type, the profile of paraxial refracting power may be properlydetermined even when surfaces other than a planar surface are used forthe reflecting surface. Preferably, however, a control system thatallows the shape of the reflecting surface to be freely transformed isprovided to make up a variable-shape mirror that corrects fluctuationsof focal position and aberrations with zooming, and is of controllableshape for focusing or zooming purposes.

Alternatively, the reflecting optical element may be constructed as bycementing a planoconcave lens to a planar portion of the prism. Toreconcile the level of correction of distortion well with the targetsize of the electronic image pickup system, it is acceptable to add apositive lens of weak power to the surface of the reflecting opticalelement located nearest to the object side. In this case, the 1-2nd lensgroup may be dispensed with.

Preferably in each of the two zoom types, the final lens group should bemade up of a single lens having an aspheric surface. This is veryeffective for correction of off-axial aberrations such as distortions,astigmatisms and comas. This lens serves to cancel out aberrationsproduced at portions of the optical system, which are present on theobject side with respect thereto; as the lens moves for focusing orother purposes, aberrations get out of balance. Thus, it is preferableto fix the final lens group.

Focusing should preferably be carried out with the second lens groupand, if any, the subsequent lens group(s) save the final lens group,because the first lens group is provided for bending the optical pathand so is not appropriate for any focusing group. It is particularlypreferable to carry out focusing with the second lens group as countedfrom the final lens group toward the object side, because that lensgroup is less vulnerable to focal length and aberration fluctuations.When, in this case, the optical system is focused on a nearby object,such second lens group is moved out. For focusing, it is then preferablethat the optical axis air separation D_(FT) between the second lensgroup and the third lens group as counted from the final lens grouptoward the object side, upon focused on an infinite-distance objectpoint at the telephoto end, satisfies the following condition (b).

0.1<D _(FT) /f _(T)<1.5  (b)

Here f_(T) is the focal length of the zoom optical system upon focusedon an infinite-distance object point at the telephoto end.

As the upper limit of 1.5 to condition (b) is exceeded, it is difficultto ensure any desired zoom ratio, and as the lower limit of 0.1 is notreached, it is impossible to allow any focusable distance.

More preferably,

0.2<D _(FT) /f _(T)<1  (b′)

Even more preferably,

0.25<D _(FT) /f _(T)<0.8  (b″)

Each of the aforesaid two zoom types should preferably comprise anadditional or third lens group located on the image side of the secondlens group and having positive refracting power, so that upon smoothingfrom the wide-angle end to the telephoto end, the second and third lensgroups move with a change in the relative spacing between them. Withthis zooming mode possible to make the zoom ratio of the optical systemhigh while its focal position upon zooming is corrected by takingadvantage of space.

Preferably in that case, the ratio between the amounts of movement M₂and M₃ of the second and third lens groups upon zooming from thewide-angle end to the telephoto end of the optical system when focusedon a point at infinity should satisfy the following range:

0.5<M ₃ /M ₂<2.0  (c)

As the upper limit of 2.0 to condition (c) is exceeded, it is impossibleto ensure any satisfactory zoom ratio or focusable distance range. Asthe lower limit of 0.5 is not reached, it is again impossible to ensureany satisfactory zoom ratio.

More preferably,

0.7<M ₃ /M ₂<1.4  (c′)

Even more preferably,

0.8<M ₃ /M ₂<1.25  (c″)

Preferable in each of the aforesaid two zoom types, the first lens group(the combined 1-1st and 1-2nd system) should remain fixed upon zoomingor focusing, because it is an optical path-bending system that isdifficult to move for mechanical reasons. It is here noted that whilethe 1-1st lens group is fixed upon zooming, the 1-2nd lens group mayremain movable because of being relatively easy to move. Preferably inthis case, the 1-2nd lens group should be designed to move in an orbitconvex toward the image side. It is also preferable that the 1-2nd lensgroup comprises, in order from its object side, two lenses, a negativeand a positive or, alternatively, one positive lens for the purpose ofcorrecting off-axis aberrations such as chromatic aberrations anddistortions.

Furthermore, if any one of such structural limitations as mentionedbelow is added to the bending zoom lens system, it is then possible tobetter its specifications and performance and simplify its construction,resulting in additional contributions to thickness reductions of theassociated image pickup systems.

Limitation 1:

In the 1-1st lens group, the negative lens group located on the objectside with respect to the reflecting optical element for bending theoptical path comprises only one negative lens convex on its object side.With this arrangement, it is possible to minimize the depth dimension ofthe optical system while the desired field angle is maintained.

Limitation 2:

In that case, it is of significance that the negative lens has somepower. In other words, the power ratio between the 1-1st lens group andthe 1-2nd lens group should preferably satisfy:

−0.8<f ₁₁ /f ₁₂<1.9  (d)

where f₁₁ is the focal length of the 1-1st lens group and f₁₂ is thefocal length of the 1-2nd lens group. Any deviation from the upper andlower limits of 1.9 and −0.8 makes the bending optical element likely tobecome large.

More preferably,

−0.6<f ₁₁ /f ₁₂<1.7  (d′)

Even more preferably,

−0.4<f ₁₁ /f ₁₂<1.5  (d″)

Limitation 3:

One of the second and third lens groups comprises a single lens, and theother comprises at least a concave lens.

The second and third lens groups move in approximately the samedirection while the relative spacing between them changes slightly sothat they can share the common use of a narrow space for zooming whilethe focal position is kept constant. Another merit is that correction ofchromatic aberrations is not necessarily brought to completion for eachlens group. In short, chromatic aberrations at the second lens group canbe corrected separately from those at the third lens group, so thateither one can be composed of a single lens, resulting in somecontribution to the size and weight reductions of the optical system.

Limitation 4:

To reduce the change in the relative spacing between the second and thethird lens group as much as possible, zooming should preferably becarried out at the magnification of the combined system of the secondand subsequent lens groups, which is around −1. To this end, it isdesired to satisfy the following condition at the telephoto end:

0.7<−β_(Rt)<2.1  (e)

Here β_(Rt) the combined magnification of the second and subsequent lensgroups at the telephoto end (upon focused on an object point atinfinity).

Any deviation from the upper and lower limits of 2.1 and 0.7 to thiscondition incurs an increase in the amount of change in the relativespacing between the second and the third lens group.

More preferably,

0.8<−β_(Rt)<1.9  (e′)

Even more preferably,

0.85<−β_(Rt)<1.7  (e″)

The present invention also provides an electronic image pickup system,characterized by comprising:

an optical path-bending zoom optical system comprising at least one lensgroup that moves only toward its object side upon zooming from thewide-angle end to the telephoto end of the optical system and at leastone reflecting optical element for, upon zooming, bending an opticalpath toward the object side with respect to the lens included in allmovable lens groups and located nearest to the object side,

said optical path being defined by an entrance surface and an exitsurface, at least one of which has a curvature, and

an electronic image pickup device located on the image side of saidoptical system.

Thus, if the reflecting optical element (prism) for bending the opticalpath is allowed to have refracting power, it is then possible todiminish the number of lens elements, making contributions to sizereductions or cost reductions.

In this case, the reflecting optical element for bending the opticalpath may be located nearest to the object side of the opticalpath-bending zooming optical system.

Thus, if the optical path-bending element is located as near to theobject side as possible, it is then possible to diminish the depthdimension of the electronic image pickup system.

Furthermore, the entrance surface of the reflecting optical element forbending the optical path may be directed toward the object side of thezoom optical system.

According to one embodiment of the present invention, there is provideda slim electronic image pickup system constructed using a zoom opticalsystem comprising, in order from its object side, a negative meniscuslens and an optical path-bending prism. If the optical path-bendingprism is designed to have an entrance surface with negative refractingpower, it is then possible to make the depth dimension of the electronicimage pickup system by far smaller, because that negative meniscus lenscan be dispensed with.

In that case, the entrance surface of the reflecting optical element forbending the optical path may be defined by an aspheric surface.

The axial curvature of the entrance surface having a negative value (theentrance surface being concave on the object side) is unfavorable inconsideration of correction of off-axis aberrations such as distortions.With the introduction of the aspheric surface, however, such aberrationscan be well corrected.

Furthermore, the exit surface of the reflecting optical element forbending the optical path may be defined by a planar surface.

It is here noted that when an aspheric surface is applied to theentrance surface as mentioned above, it is difficult to ensure anydesired decentration accuracy between that surface and the exit surface.However, if another surface (exit surface) is defined by a planarsurface, it is then possible to slacken off demand for decentrationaccuracy between both surfaces.

The lens group that moves only toward the object side upon zooming fromthe wide-angle end to the telephoto end is made up of two positivelenses and at least one negative lens. It is then acceptable that atleast each positive lens and the negative lens are cemented together.

In the lens group that moves only toward the object side upon zoomingform the wide-angle end to the telephoto end, there is a tendency foraberrations to deteriorate largely due to relative decentration betweenthe positive lens and the negative lens. It is thus preferable that thepositive and the negative lens are cemented to the greatest extentpracticable.

The lens group that moves only toward the object side upon zooming fromthe wide-angle end to the telephoto end is made up of two positivelenses and at least one negative lens. It is then acceptable that atleast one positive lens and the negative lens are cemented together.

Thus, the lens group that moves only toward the object side upon zoomingfrom the wide-angle end to the telephoto end should comprise at leasttwo positive lenses and at least one negative lens, at least three inall.

Next, how and why the thickness of filters is reduced is now explained.In an electronic image pickup system, an infrared absorption filterhaving a certain thickness is usually inserted between an image pickupdevice and its object side and positioned nearer to the object side, sothat the incidence of infrared light on the image pickup plane isprevented. Here consider the case where this filter is replaced by acoating devoid of thickness. In addition to the fact that the systembecomes thin as a matter of course, there are spillover effects. When anear-infrared sharp cut coat having a transmittance of at least 80% at600 nm and a transmittance of up to 10% at 700 nm is introduced betweenan image pickup device in the rear of the zoom lens system and theobject side of the system and nearer to the object side, thetransmittance on the red side is relatively higher that that of theabsorption type, so that the tendency of bluish purple to turn intomagenta—a defect of a complementary mosaic filter-inserted CCD—isdiminished by gain control and there can be obtained color reproductioncomparable to that by a CCD having a primary colors filter. On the otherhand, a complementary filter is higher in substantial sensitivity andmore favorable in resolution than a primary colors filter-inserted CCDdue to its high transmitted energy, and provides a great merit when usedin combination with a small-size CCD. Regarding an optical low-passfilter that is another filter, too, its total thickness, t_(LPF), shouldpreferably comply with the following condition:

0.15a<t _(LPF)<0.45a (mm)  (f)

Here a is the horizontal pixel pitch (in μm) of the electronic imagepickup device.

Reducing the thickness of the optical low-pass filter, too, is effectivefor making the thickness of the zoom lens upon received in the lensmount; however, this is generally not preferred because the moirépreventive effect becomes slender. On the other hand, as the pixel pitchbecomes small, the contrast of frequency components greater than Nyquistcriterion decreases under the influence of diffraction of animage-formation lens and, consequently, the decrease in the moirépreventive effect is more or less acceptable. For instance, it is knownthat when three different filters having crystallographic axes indirections where upon projected onto the image plane, the azimuth angleis horizontal (=0°) and ±45° are used while they are put one uponanother, some moiré preventive effect is obtainable. According to thespecifications known to make the filter assembly thinnest, each filteris displaced by a μm in the horizontal and by SQRT(1/2)*a μm in the ±45°directions. Here SQRT means a square root. The then filter thickness isapproximately given by [1+2*SQRT(1/2)]*a/5.88 (mm). This is thespecification where the contrast is reduced down to zero at a frequencycorresponding just to Nyquist criterion. At a thickness a few % to a fewtens of % smaller than this, a little more contrast of the frequencycorresponding to Nyquist criterion appears; however, this can besuppressed under the influence of the aforesaid diffraction.

In other filter embodiments where two filters are placed one uponanother or one single filter is used, too, it is preferable to complywith condition (f). When the upper limit of 0.45a is exceeded, theoptical low-pass filter becomes too thick, contrary to size reductionrequirements. When the lower limit of 0.15a is not reached, moiréremoval becomes insufficient. In this condition, a should be 5 μm orless.

When a is 4 μm or less or where the optical low-pass filter is moresusceptible to diffraction, it is preferable that

0.13a<t _(LPF)0.42a  (f′)

It is also acceptable thatwhen a is 4 μm or greater,

-   -   0.3a<t_(LPF)<0.4a provided that three filters are placed one        upon another and a<5 μm    -   0.2a<t_(LPF)<0.28a provided that two filters are placed one upon        another and a<5 μm    -   0.1a<t_(LPF)<0.16a provided that one filter is used and a<5 μm        when a is 4 μm or less,    -   0.25a<t_(LPF)<0.37a provided that three filters are placed one        upon another    -   0.16a<t_(LPF)<0.25a provided that two filters are placed one        upon another    -   0.08a<t_(LPF)<0.14a provided that one filter is used

When an image pickup device having a small pixel pitch is used, there isdegradation in image quality under the influence of diffraction effectby stop-down. In this case, the electronic image pickup system isdesigned in such a way as to have a plurality of apertures each of fixedaperture size, one of which can be inserted into any one of opticalpaths between the lens surface located nearest to the image side of thefirst lens group and the lens surface located nearest to the object sideof the third lens group and can be replaced with another as well, sothat illuminance on the image plane can be adjusted. Then, media whosetransmittances with respect to 550 nm are different but less than 80%are filled in some of the plurality of apertures for light quantitycontrol. Alternatively, when control is carried out in such a way as toprovide a light quantity corresponding to such an F-number as given by a(μm)/F-number<4.0, it is preferable to fill the apertures with mediumwhose transmittance with respect to 550 nm are different but less than80%. In the range of the full-aperture value to values deviating fromthe aforesaid condition as an example, any medium is not used or dummymedia having a transmittance of at least 91% with respect to 550 nm areused. In the range of the aforesaid condition, it is preferable tocontrol the quantity of light with an ND filter or the like, rather thanto decrease the diameter of the aperture stop to such an extent that theinfluence of diffraction appears.

Alternatively, it is acceptable to uniformly reduce the diameters of aplurality of apertures inversely with the F-numbers, so that opticallow-pass filters having different frequency characteristics can beinserted in place of ND filters. As degradation by diffraction becomesworse with stop-down, it is desirable that the smaller the aperturediameter, the higher the frequency characteristics the optical low-passfilters have.

In order to slim down an electronic image pickup system, not onlycontrivances for an associated optical system but also contrivances forits mechanical mechanism and layouts are of importance. In particular,it is important to take advantage of the collapsible lens mount typewherein the optical system is received in the lens mount. For the lensarrangement of the present invention, it is preferable to make use of aspecific collapsible lens mount type wherein the reflecting opticalelement already in the optical system body is relocated from the opticalpath in a separate space in the optical system body, and the lens groupsthat are located on the object side with respect to the reflectingoptical element and move out of the optical system body duringphototaking are received in the resulting space on the optical path.

This specific collapsible lens mount type may also be applied to anoptical system having a lens arrangement other than that of the presentinvention, provided that it comprises, in order from its object side, afirst lens group of negative power, a reflecting optical element forbending an optical path and a second lens group of positive power. Thereflecting optical element is relocated from the optical path in aseparate space in the optical system body, so that the first lens groupis received in the resulting space on the optical path.

Preferably in this case, while the first lens group is received in theoptical system body, the second lens group is shifted to the image sidewith respect to the position farthest away from the image plane at thetime of phototaking. There is also a moving space for zooming orfocusing subsequent to the second lens group. To make effective use ofthat space during lens reception or the like, the second lens is putdown as close to the image side as possible and, if required, thereflecting optical element is shifted to the image side, so that thefirst lens group is received in place.

For instance, when the reflecting optical element is constructed of areflecting mirror comprising a thin plate with a reflecting mirrorcoating applied thereon, the first lens group can be received in placewith no need of any separate space, because the reflecting mirror isrelocated vertically to the optical axis with the reflecting surfacebent.

Besides, each of lenses other than the reflecting optical element may betilted or shifted during lens reception, thereby creating some receptionspace.

When the prism is constructed of a solid outer shell with a liquid orthe like filled therein, thickness reductions may be achieved byremoving the liquid from inside.

It is noted that with an optical system using a reflecting opticalelement, the following embodiments are feasible.

The best embodiment is a TTL single-lens reflecting optical system fusedwith a Porro prism type finder.

In one typical embodiment of this optical system, between a phototakingoptical system including a reflecting optical element and an imagepickup device there is interposed a second reflecting surface forsplitting (in time division, amplitude division or any other modes) anoptical path toward a side nearly at right angles with a plane includingan optical axis before and after reflection at the reflecting opticalelement. A third reflecting surface is disposed along the opposite side,with the normal lying in much the same plane with respect to the normalto the second reflecting surface and nearly at right angles therewith.Furthermore, a fourth reflecting surface is disposed in such a way thatan optical path after reflection thereat runs parallel with the opticalaxis of the entrance side of the phototaking optical system. This makesa great deal of contribution to the thickness reductions of a camera.

In the second embodiment wherein the reflecting optical element and anoptical system on the object side with respect thereto is designed to berotatable with respect to the vicinity of the entrance pupil of aphototaking optical system or the like, it is possible to change thephototaking direction. Alternatively, optical prevention of cameramovements is possible.

Still other objects and advantages of the invention will in part beobvious and will in part be apparent from the specification.

The invention accordingly comprises the features of construction,combinations of elements, and arrangement of parts which will beexemplified in the construction hereinafter set forth, and the scope ofthe invention will be indicated in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1( a) to 1(c) are sections in schematic illustrative of Example 1of the optical path-bending zoom optical system used with the electronicimage pickup system of the invention at the telephoto end (a),intermediate state (b) and wide-angle end (c) when the opticalpath-bending zoom optical system is focused on an object point atinfinity.

FIGS. 2( a) to 2(c) are sections in schematic illustrative of Example 2of the optical path bending-zoom optical system, similar to FIGS. 1( a)to 1(c).

FIGS. 3( a) to 3(c) are sections in schematic illustrative of Example 3of the optical path-bending zoom optical system, similar to FIGS. 1( a)to 1(c).

FIGS. 4( a) to 4(c) are sections in schematic illustrative of Example 4of the optical path-bending zoom optical system, similar to FIGS. 1( a)to 1(c).

FIGS. 5( a) to 5(c) are sections in schematic illustrative of Example 5of the optical path-bending zoom optical system, similar to FIGS. 1( a)to 1(c).

FIGS. 6( a) to 6(c) are sections in schematic illustrative of Example 6of the optical path-bending zoom optical system, similar to FIGS. 1( a)to 1(c).

FIGS. 7( a) to 7(c) are sections in schematic illustrative of Example 7of the optical path-bending zoom optical system, similar to FIGS. 1( a)to 1(c).

FIGS. 8( a) to 8(c) are sections in schematic illustrative of Example 8of the optical path-bending zoom optical system, similar to FIGS. 1( a)to 1(c).

FIGS. 9( a) to 9(c) are sections in schematic illustrative of Example 9of the optical path-bending zoom optical system, similar to FIGS. 1( a)to 1(c).

FIGS. 10( a) to 10(c) are sections in schematic illustrative of Example10 of the optical path-bending zoom optical system, similar to FIGS. 1(a) to 1(c).

FIGS. 11( a) to 11(c) are sections in schematic illustrative of Example11 of the optical path-bending zoom optical system, similar to FIGS. 1(a) to 1(c).

FIGS. 12( a) to 12(c) are sections in schematic illustrative of Example12 of the optical path-bending zoom optical system, similar to FIGS. 1(a) to 1(c).

FIGS. 13( a) to 13(c) are aberration diagrams of Example 1 upon focusedon an object point at infinity.

FIGS. 14( a) to 14(c) are aberration diagrams of Example 12 upon focusedon an object point at infinity.

FIGS. 15( a) and 15(b) are conceptual schematics illustrative of oneembodiment of how to receive the optical path bending-zoom opticalsystem of the invention in place.

FIG. 16 is a conceptual schematic illustrative of one embodiment of howto receive the optical system body in place when the reflecting opticalelement for bending an optical path is constructed of a mirror.

FIG. 17 is a conceptual schematic illustrative of another embodiment ofhow to receive the optical system in place when the reflecting opticalelement for bending an optical path is constructed of a mirror.

FIGS. 18( a) and 18(b) are conceptual schematics illustrative of oneembodiment of how to receive the optical system in place when thereflecting optical element for bending an optical path is constructed ofa liquid or transformable prism.

FIG. 19 is a conceptual schematic illustrative of how to carry outfocusing when the reflecting optical element for bending an optical pathis constructed of a variable-shape mirror.

FIG. 20 is a conceptual schematic illustrative of the surface shape of avariable-shape mirror.

FIG. 21 is a conceptual schematic illustrative of how to correct cameramovements when the reflecting optical element for bending an opticalpath is constructed of a variable-shape mirror.

FIG. 22 is a conceptual schematic illustrative of how to split a finderoptical path from the optical path-bending zoom optical system.

FIG. 23 is a diagram indicative of the transmittance characteristics ofone example of the near-infrared sharp cut coat.

FIG. 24 is a diagram indicative of the transmittance characteristics ofone example of the color filter located on the exit surface side of thelow-pass filter.

FIG. 25 is a schematic illustrative of how the color filter elements arearranged in the complementary mosaic filter.

FIG. 26 is a diagram indicative of one example of the wavelengthcharacteristics of the complementary mosaic filter.

FIG. 27 is a detailed perspective view illustrative of one example ofthe aperture stop portion in each example.

FIGS. 28( a) and 28(b) are illustrative in detail of another example ofthe aperture stop in each example.

FIG. 29 is a front perspective schematic illustrative of the outsideshape of a digital camera with the inventive optical path-bending zoomoptical system built therein.

FIG. 30 is a rear perspective schematic of the digital camera of FIG.29.

FIG. 31 is a sectional schematic of the digital camera of FIG. 29.

FIG. 32 is a front perspective view of an uncovered personal computer inwhich the inventive optical path-bending zoom optical system is built inthe form of an objective optical system.

FIG. 33 is a sectional schematic of a phototaking optical system for apersonal computer.

FIG. 34 is a side view of FIG. 32.

FIGS. 35( a) to 35(c) are a front and a side view of a cellular phonewith the inventive optical path-bending zoom optical system built in asan objective optical system, and a sectional view of a phototakingoptical system therefore, respectively.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Examples 1 to 12 of the optical path-bending zoom optical system usedwith the electronic image pickup system of the invention are nowexplained. Sectional lens configurations of these examples at thetelephoto end (a), intermediate state (b) and wide-angle end (c) uponfocused on an object point at infinity are shown in FIGS. 1 through 12wherein G1 represents a first lens group, G1-1 a 1-1st lens group, G1-2a 1-2nd lens group, G2 a second lens group, G3 a third lens group, G4 afourth lens group, G5 a fifth lens group, P an optical path-bendingprism, S an aperture stop (in an independent case), IF a near infraredcut filter, IC a near infrared cut coat surface, LF a low-pass filter,CG a cover glass for an electronic image pickup device CCD, and I theimage plane of CCD. The near infrared cut filter IF and low-pass filterLF or the near infrared cut coat surface IC, low-pass filter LF andcover glass CG, located in order from the object side of the zoomoptical system, are fixedly provided between the final lens group andthe image plane I.

As shown in FIG. 1, Example 1 is directed to an optical path-bendingzoom optical system made up of a 1-1st lens group G1-1 consisting of anoptical path-bending prism P equivalent to a double-concave negativelens, a 1-2nd lens group G1-2 consisting of a double-convex positivelens, a second lens group G1 consisting of an aperture stop and adouble-convex positive lens, a third lens group G3 consisting of adoublet composed of a double-convex positive lens and a double-concavenegative lens and a double-convex positive lens, a fourth lens group G4consisting of a negative meniscus lens convex on its object side, and afifth lens group G5 consisting of a double-convex positive lens. Forzooming from the wide-angle end to the telephoto end of the zoom opticalsystem, the second lens group G2 and the third lens group G3 move towardthe object side while the spacing between them becomes wide and thennarrow, and the fourth lens group G4 and the third lens group G3 movetoward the object side while the spacing between them becomes wide.

Four aspheric surfaces are used, one at the object-side surface of thedouble-convex positive lens in the 1-2nd lens group G1-2, one at theobject-side surface of the double-convex positive lens in the secondlens group G2, one at the image-side surface of the negative meniscuslens in the fourth lens group G4, and one at the image-side surface ofthe double-convex positive lens in the fifth lens group G5.

As shown in FIG. 2, Example 2 is directed to an optical path-bendingzoom optical system made up of a 1-1st lens group consisting of anoptical path bending prism P equivalent to a double-concave negativelens, a 1-2nd lens group consisting of a double-convex positive lens, anindependently moving aperture stop S, a second lens group G2 consistingof a double-convex positive lens, a positive meniscus lens convex on itsobject side and a negative meniscus lens convex on its object side, athird lens group G3 consisting of a double-convex positive lens and anegative meniscus lens convex on its image side, and a fourth lens groupG4 consisting of a positive meniscus lens convex on its object side. Forzooming from the wide-angle end to the telephoto end of the zoom opticalsystem, the second lens group G2 and the third lens group move towardthe object side while the spacing between them becomes wide. Theaperture stop S located between the 1-2nd lens group 1-2 and the secondlens group G2, too, moves toward the object side while the spacingbetween the 1-2nd lens group G1-2 and the fourth lens group G4 becomesnarrow.

Three aspheric surfaces are used, one at the object-side surface of thedouble-convex positive lens in the 1-2nd lens group G1-2, one at thesurface of the second lens group G2 located nearest to its object side,and one at the object-side surface of the positive meniscus lens in thefourth lens group G4.

As shown in FIG. 3, Example 3 is directed to an optical path-bendingzoom optical system made up of a 1-1st lens group G1-1 consisting of anegative meniscus lens convex on its object side and an optical pathbending prism P equivalent to a plane-parallel plate, a 1-2nd lens groupG1-2 consisting of a double-concave negative lens and a double-convexpositive lens, a second lens group G2 consisting of an aperture stop anda double-convex positive lens, a third lens group G3 consisting of adouble-convex positive lens, a negative meniscus lens convex on itsobject side, a double-convex positive lens and a negative meniscus lensconvex on its image side, and a fourth lens group G4 consisting of apositive meniscus lens convex on its image side. For zooming from thewide-angle end to the telephoto end of the zoom optical system, thesecond lens group G2 and the third lens group G3 move toward the objectside of the zoom optical system while the spacing between them becomeswide and then narrow.

Three aspheric surface are used, one at the object side-surface of thedouble-convex positive lens in the 1-2nd group G1-2, one at the surfaceof the third lens group G3 located nearest to its object side, and oneat the object side-surface of the positive meniscus lens in the fourthlens group G4.

As shown in FIG. 4, Example 4 is directed to an optical path-bendingzoom optical system made up of a 1-1st lens group G1-1 consisting of anegative meniscus lens convex on its object side and an optical pathbending prism P equivalent to a plane-parallel plate, a 1-2nd lens groupG1-2 consisting of a double-concave negative lens and a double-convexpositive lens, a second lens group G2 consisting of an aperture stop, adouble-convex positive lens, a double-convex positive lens and anegative meniscus lens convex on its object side, a third lens group G3consisting of a positive meniscus lens convex on its object side, and afourth lens group G4 consisting of a positive meniscus lens convex onits image side. For zooming from the wide-angle end to the telephoto endof the zoom optical system, the second lens group G2 and the third lensgroup G3 move toward the object side of the zoom optical system whilethe spacing between them becomes wide and then narrow.

Three aspheric surfaces are used, one at the object-side surface of thedouble-convex positive lens in the 1-2nd lens group G1-2, one at theobject-side surface of the double-convex positive lens located after thestop in the second lens group G2, and one at the object-side surface ofthe positive meniscus lens in the second lens group G4.

As shown in FIG. 5, Example 5 is directed to an optical path-bendingzoom optical system made up of a first lens group G1 consisting of apositive meniscus lens convex on its object side, a negative meniscuslens convex on its object side and an optical path bending prism Pequivalent to a plane-parallel plate, a second lens group G2 consistingof an aperture stop and a double-convex positive lens, a third lensgroup G3 consisting of a doublet consisting of a double-convex positivelens and a double-concave negative lens and a double-convex positivelens, a fourth lens group G4 consisting of a negative meniscus lensconvex on its object side, and a fifth lens group G5 consisting of apositive meniscus lens convex on its object side. For zooming from thewide-angle end to the telephoto end of the zoom optical system, thesecond lens group G2 and the third lens group G3 move toward the objectside of the zoom optical system while the spacing between them becomeswide and then narrow, the third lens group G3 and the fourth lens groupG4 move toward the object side while the spacing between them becomeswide, and the fifth lens group moves slightly toward the image side ofthe zoom optical system.

Four aspheric surfaces are used, one at the image-side surface of thedouble-convex positive lens in the first lens group G1, one at theobject side-surface of the double-convex positive lens in the secondlens group G2, one at the image side-surface of the negative meniscuslens in the fourth lens group G4 and one at the image side-surface ofthe positive meniscus lens in the fifth lens group G5.

As shown in FIG. 6, Example 6 is directed to an optical path-bendingzoom optical system made up of a first lens group G1 consisting of adouble-convex positive lens, a double-concave negative lens and anoptical path bending prism P equivalent to a plane-parallel plate, asecond lens group G2 consisting of an aperture stop and a doubletconsisting of a double-convex positive lens and a negative meniscus lensconvex on its image side, a third lens group G3 consisting of a negativemeniscus lens convex on its object side, and a fourth lens group G4consisting of a double-convex positive lens. For zooming from thewide-angle end to the telephoto end of the zoom optical system, thesecond lens group G2 and the third lens group G3 move toward the objectside of the zoom optical system while the spacing between them becomeswide, and the fourth lens group G4 moves slightly toward the object sideon the telephoto side while it moves in a convex orbit toward the imageside of the zoom lens optical system.

Three aspheric surfaces are used, one at the object side-surface of thedouble-concave negative lens in the first lens group G1, one at thesurface of the second lens group G2 located nearest to its object sideand one at the image side-surface of the negative meniscus lens in thethird lens group G3.

As shown in FIG. 7, Example 7 is directed to an optical path-bendingzoom optical system made up of a 1-1st lens group G1-1 consisting of anegative meniscus lens convex on its object side and an optical pathbending prism P equivalent to a plane-parallel plate, a 1-2nd lens groupG1-2 consisting of a double-concave positive lens and a double-convexpositive lens, a second lens group G2 consisting of an aperture stop, adouble-convex positive lens, a doublet composed of a double-convexpositive lens and a negative meniscus lens convex on its image side, athird lens group G3 consisting of a positive meniscus lens convex on itsimage side, and a fourth lens group G4 consisting of a positive meniscuslens convex on its image side. For zooming from the wide-angle end tothe telephoto end of the zoom optical system, the second lens group G2and the third lens group G3 move toward the object side of the zoomoptical system while the spacing between them becomes wide and thennarrow.

Three aspheric surfaces are used, one at the image side-surface of thenegative meniscus lens in the 1-1st lens group G1-1, one at the surfaceof the second lens group G2 located nearest to the object side and oneat the object side-surface of the positive meniscus lens in the fourthlens group G4.

As shown in FIG. 8, Example 8 is directed to an optical path-bendingzoom optical system made up of a 1-1st lens group G1-1 consisting of anegative meniscus lens convex on its object side and an optical pathbending prism P equivalent to a plane-parallel plate, a 1-2nd lens groupG1-2 consisting of a double-concave negative lens and a positivemeniscus lens convex on its object side, a second lens group G2consisting of an aperture stop, a double-convex positive lens and adoublet composed of a double-convex positive lens and a double-concavenegative lens, a third lens group G3 consisting of a positive meniscuslens convex on its image side, and a fourth lens group G4, consisting ofa positive meniscus lens convex on its image side. For zooming from thewide-angle end to the telephoto end of the zoom optical system, thesecond lens group G2 and the third lens group G3 move toward the objectside of the zoom optical system while the spacing between them becomeswide and then narrow.

Three aspheric surfaces are used, one at the object side-surface of thenegative meniscus lens in the 1-1st lens group G1-1, the surface of thesecond lens group G2 located nearest to its object side and one at theimage side-surface of the positive meniscus lens in the fourth lensgroup G4.

As shown in FIG. 9, Example 9 is directed to an optical path-bendingzoom optical system made up of a 1-1st lens group G1-1 consisting of anegative meniscus lens convex on its object side and an optical pathbending prism P equivalent to a plane-parallel plate, a 1-2nd lens groupG1-2 consisting of a negative meniscus lens convex on its object sideand a positive meniscus lens convex on its object side, a second lensgroup G2 consisting of an aperture stop and a double-convex positivelens, a third lens group G3 consisting of a double-convex positive lens,a negative meniscus lens convex on its object side and a doubletcomposed of a double-convex positive lens and a double-concave negativelens, and a fourth lens group G4 consisting of a positive meniscus lensconvex on its image side. For zooming from the wide-angle end to thetelephoto end of the zoom optical system, the second lens group G2 andthe third lens group G3 move toward the object side while the spacingbetween them becomes wide and then narrow.

Three aspheric surfaces are used, one at the image side-surface of thenegative meniscus lens in the 1-2nd lens group G1-2, one at the surfaceof the third lens group G3 located nearest to its object side and one atthe object side-surface of the positive meniscus lens in the fourth lensgroup G4.

As shown in FIG. 10, Example 10 is directed to an optical path-bendingzoom optical system made up of a 1-1st lens group G1-1 consisting of anegative meniscus lens convex on its object side and an optical pathbending prism P equivalent to a plane-parallel plate, a 1-2nd lens groupG1-2 consisting of a negative meniscus lens convex on its object sideand a positive meniscus lens convex on its object side, a second lensgroup G2 consisting of an aperture stop and a doublet composed of adouble-convex positive lens and a negative meniscus lens convex on itsimage plane side, a third lens group G3 consisting of a positivemeniscus lens convex on its object side, a negative meniscus lens convexon its object side and a doublet composed of a double-convex positivelens and a double-concave negative lens, and a fourth lens group G4consisting of a positive meniscus lens convex on its image plane side.For zooming from the wide-angle end to the telephoto end of the zoomoptical system, the second lens group G2 and the third lens group G3move toward the object side of the zoom lens system while the spacingbetween them becomes wide and then narrow.

Three aspheric surfaces are used, one at the image plane side-surface ofthe negative meniscus lens in the 1-2nd lens group G1-2, one at thesurface of the third lens group G3 located nearest to its object sideand one at the object side-surface of the positive meniscus lens in thefourth lens group G4.

As shown in FIG. 11, Example 11 is directed to an optical path-bendingzoom optical system made up of a 1-1st lens group G1-1 consisting of anegative meniscus lens convex on its object side and an optical pathbending prism P equivalent to a plane-parallel plate, a 1-2nd lens groupconsisting of a negative meniscus lens convex on its object side and apositive meniscus lens convex on its object side, a second lens group G2consisting of an aperture stop and a doublet composed of a double-convexpositive lens and a negative meniscus lens convex on its image planeside, a third lens group G3 consisting of a positive meniscus lensconvex on its object side and a doublet composed of a planoconvexpositive lens and a planoconcave negative lens, and a fourth lens groupG4 consisting of a double-convex positive lens. For zooming from thewide-angle end to the telephoto end of the zoom optical system, thesecond lens group G2 and the third lens group G3 move toward the objectside of the zoom optical system while the spacing between them becomeswide and then narrow.

Three aspheric surfaces are used, one at the image plane side-surface ofthe negative meniscus lens in the 1-2nd lens group G1-2, one at theobject side-surface of the positive meniscus lens in the third lensgroup G3 and one at the image plane side-surface of the double-convexpositive lens in the fourth lens group G4.

As shown in FIG. 12, Example 12 is directed to an optical path-bendingzoom optical system made up of a 1-1st lens group G1-1 consisting of anoptical path bending prism P equivalent to a planoconcave negative lens,a 1-2nd lens group G1-2 consisting of a doublet composed of a negativemeniscus lens concave on its object side and a positive meniscus lensconcave on its object side, a second lens group G2 consisting of apositive meniscus lens convex on its object side and a negative meniscuslens convex on its object side, a third lens group G3 consisting of adouble-convex positive lens, and a fourth lens group G4 consisting of apositive meniscus lens convex on its image plane side. For zooming fromthe wide-angle end to the telephoto end of the zoom optical system, thesecond lens group G2 and the third lens group G3 move toward the objectside of the zoom optical system while the spacing between them becomeswide and then narrow.

Three aspheric surfaces are used, one at the object side-surface of theoptical path bending prism P in the 1-1st lens group G1-1, one at thesurface of the second lens group G2 located nearest to its object sideand one at the image plane side-surface of the positive meniscus lens inthe fourth lens group G4.

Set out below are the numerical data on each example. Symbols usedhereinafter but not hereinbefore have the following meanings:

-   f: focal length of the zoom optical system-   2ω: field angle-   F_(NO): F-number-   WE: wide-angle end-   ST: standard or intermediate state-   TE: telephoto end-   r₁, r₂, . . . : radius of curvature of each lens element-   d₁, d₂, . . . : spacing between the adjacent lens elements-   n_(d1)/n_(d2), . . . : d-line refractive index of each lens element-   ν_(d1), ν_(d2), . . . : Abbe constant of each lens element

Here let x be an optical axis on condition that the direction ofpropagation of light is positive and y be a direction perpendicular tothe optical axis. Then, aspheric configuration is given by

x=(y ² /r)/[1+{1−(K+1)(y/r)²}^(1/2) ]+A ₄ y ⁴ +A ₈ y ⁸ +A ₁₀ y ¹⁰

where r is a paraxial radius of curvature, K is a conical coefficient,and A₄, A₆, A₈ and A₁₀ are the fourth, sixth, eighth and tenth asphericcoefficients, respectively.

EXAMPLE 1

r₁ = −26.8147 d₁ = 3.8000 n_(d1) = 1.73400 ν_(d1) = 51.47 r₂ = ∞(Mirror) d₂ = 3.2000 n_(d2) = 1.73400 ν_(d2) = 51.47 r₃ = 6.2254 d₃ =1.7202 r₄ = 424.9864 (Aspheric) d₄ = 2.4297 n_(d3) = 1.84666 ν_(d3) =23.78 r₅ = −48.1247 d₅ = (Variable) r₆ = ∞ (Stop) d₆ = 0.5000 r₇ =17.8731 (Aspheric) d₇ = 2.0000 n_(d4) = 1.58913 ν_(d4) = 61.26 r₈ =−16.6911 d₈ = (Variable) r₉ = 7.9903 d₉ = 6.2379 n_(d5) = 1.48749 ν_(d5)= 70.23 r₁₀ = −14.7007 d₁₀ = 0.8488 n_(d6) = 1.84666 ν_(d6) = 23.78 r₁₁= 7.0178 d₁₁ = 1.1903 r₁₂ = 11.2307 d₁₂ = 1.6307 n_(d7) = 1.84666 ν_(d7)= 23.78 r₁₃ = −24.5400 d₁₃ = (Variable) r₁₄ = 18.1763 d₁₄ = 0.5000n_(d8) = 1.84666 ν_(d8) = 23.78 r₁₅ = 5.9110 (Aspheric) d₁₅ = (Variable)r₁₆ = 14.1876 d₁₆ = 3.0000 n_(d9) = 1.58913 ν_(d9) = 61.26 r₁₇ = −7.1178(Aspheric) d₁₇ = 0.5006 r₁₈ = ∞ d₁₈ = 0.8000 n_(d10) = 1.51633 ν_(d10) =64.14 r₁₉ = ∞ d₁₉ = 1.8000 n_(d11) = 1.54771 ν_(d11) = 62.84 r₂₀ = ∞ d₂₀= 0.5000 r₂₁ = ∞ d₂₁ = 0.5000 n_(d12) = 1.51633 ν_(d12) = 64.14 r₂₂ = ∞d₂₂ = 1.1914 r₂₃ = ∞ (Image Plane) Aspherical Coefficients 4th surface K= 0.0195 A₄ = 5.4111 × 10⁻⁴ A₆ = 2.1984 × 10⁻⁶ A₈ = 4.5957 × 10⁻⁷ A₁₀ =−1.0754 × 10⁻⁸ 7th surface K = 5.8821 A₄ = −2.7575 × 10⁻⁴ A₆ = 5.8194 ×10⁻⁶ A₈ = −7.9649 × 10⁻⁷ A₁₀ = 3.4848 × 10⁻⁸ 15th surface K = −3.6043 A₄= 2.6150 × 10⁻³ A₆ = −8.5623 × 10⁻⁶ A₈ = −2.8972 × 10⁻⁶ A₁₀ = 1.5174 ×10⁻⁷ 17th surface K = 0.8882 A₄ = 1.1140 × 10⁻³ A₆ = −8.5962 × 10⁻⁶ A₈ =3.9677 × 10⁻⁷ A₁₀ = 3.1086 × 10⁻⁸ Zooming Data (∞) WE ST TE f (mm)4.59000 8.95000 13.23000 FNO 2.8316 3.8724 4.6438 2ω (°) 65.5 34.0 23.0d₅ 12.93741 5.34873 2.00000 d₈ 2.61607 2.85689 0.50000 d₁₃ 1.096715.22639 10.38165 d₁₅ 1.00016 4.21405 4.71724

EXAMPLE 2

r₁ = −129.7294 d₁ = 4.5500 n_(d1) = 1.80400 ν_(d1) = 46.57 r₂ = ∞(Mirror) d₂ = 4.0019 n_(d2) = 1.80400 ν_(d2) = 46.57 r₃ = 5.3898 d₃ =1.6465 r₄ = 30.0332 (Aspheric) d₄ = 1.4609 n_(d3) = 1.84666 ν_(d3) =23.78 r₅ = −35.8611 d₅ = (Variable) r₆ = ∞ (Stop) d₆ = (Variable) r₇ =9.6063 (Aspheric) d₇ = 2.7296 n_(d4) = 1.48749 ν_(d4) = 70.23 r₈ =−30.8421 d₈ = 0.1469 r₉ = 10.1172 d₉ = 2.1277 n_(d5) = 1.69680 ν_(d5) =55.53 r₁₀ = 97.1974 d₁₀ = 0.0500 r₁₁ = 12.1982 d₁₁ = 0.7949 n_(d6) =1.84666 ν_(d6) = 23.78 r₁₂ = 5.7271 d₁₂ = (Variable) r₁₃ = 14.2960 d₁₃ =4.0342 n_(d7) = 1.48749 ν_(d7) = 70.23 r₁₄ = −15.7323 d₁₄ = 0.1401 r₁₅ =−18.5671 d₁₅ = 1.1241 n_(d8) = 1.84666 ν_(d8) = 23.78 r₁₆ = −29.8834 d₁₆= (Variable) r₁₇ = 46.3841 (Aspheric) d₁₇ = 1.1752 n_(d9) = 1.58913ν_(d9) = 61.26 r₁₈ = 541.6142 d₁₈ = 0.4453 r₁₉ = ∞ d₁₉ = 0.8000 n_(d10)= 1.51633 ν_(d10) = 64.14 r₂₀ = ∞ d₂₀ = 1.8000 n_(d11) = 1.54771 ν_(d11)= 62.84 r₂₁ = ∞ d₂₁ = 0.5000 r₂₂ = ∞ d₂₂ = 0.5000 n_(d12) = 1.51633ν_(d12) = 64.14 r₂₃ = ∞ d₂₃ = 1.2588 r₂₄ = ∞ (Image Plane) AsphericalCoefficients 4th surface K = 42.6072 A₄ = 4.5281 × 10⁻⁴ A₆ = −1.2752 ×10⁻⁶ A₈ = 2.9327 × 10⁻⁷ A₁₀ = 0 7th surface K = 0 A₄ = −2.9136 × 10⁻⁴ A₆= −7.7511 × 10⁻⁷ A₈ = 2.4221 × 10⁻⁸ A₁₀ = 0 17th surface K = 0 A₄ =−8.0585 × 10⁻⁴ A₆ = 1.7583 × 10⁻⁵ A₈ = −1.1309 × 10⁻⁶ A₁₀ = 0 ZoomingData (∞) WE ST TE f (mm) 4.71141 7.84455 13.21508 FNO 2.8000 3.66125.0650 2ω (°) 67.8 41.2 24.8 d₅ 10.20144 4.70557 1.12127 d₆ 7.090245.59391 1.24849 d₁₂ 3.08267 9.70509 10.04403 d₁₆ 0.98577 1.28696 8.72623

EXAMPLE 3

r₁ = 22.0799 d₁ = 0.7823 n_(d1) = 1.80400 ν_(d1) = 46.57 r₂ = 7.0105 d₂= 1.1905 r₃ = ∞ d₃ = 3.8000 n_(d2) = 1.80400 ν_(d2) = 46.57 r₄ = ∞(Mirror) d₄ = 3.4483 n_(d3) = 1.80400 ν_(d3) = 46.57 r₅ = ∞ d₅ = 0.4000r₆ = −43.4610 d₆ = 0.7742 n_(d4) = 1.77250 ν_(d4) = 49.60 r₇ = 9.6384 d₇= 0.6369 r₈ = 19.1908 d₈ = 1.6810 n_(d5) = 1.84666 ν_(d5) = 23.78(Aspheric) r₉ = −40.1274 d₉ = (Variable) r₁₀ = ∞ (Stop) d₁₀ = 0.5000 r₁₁= 85.1662 d₁₁ = 1.5117 n_(d6) = 1.58913 ν_(d6) = 61.26 r₁₂ = −18.3807d₁₂ = (Variable) r₁₃ = 5.5347 d₁₃ = 2.9473 n_(d7) = 1.48749 ν_(d7) =70.23 (Aspheric) r₁₄ = −102.8346 d₁₄ = 0.1500 r₁₅ = 68.5128 d₁₅ = 3.4582n_(d8) = 1.84666 ν_(d8) = 23.78 r₁₆ = 5.6774 d₁₆ = 2.1376 r₁₇ = 7.8453d₁₇ = 2.3148 n_(d9) = 1.60542 ν_(d9) = 45.99 r₁₈ = −12.6010 d₁₈ = 0.5441r₁₉ = −6.0465 d₁₉ = 0.7255 n_(d10) = 1.61800 ν_(d10) = 63.33 r₂₀ =−17.9513 d₂₀ = (Variable) r₂₁ = −17.2238 d₂₁ = 1.4117 n_(d11) = 1.58913ν_(d11) = 61.26 (Aspheric) r₂₂ = −9.8048 d₂₂ = 0.5599 r₂₃ = ∞ d₂₃ =0.8000 n_(d12) = 1.51633 ν_(d12) = 64.14 r₂₄ = ∞ d₂₄ = 1.8000 n_(d13) =1.54771 ν_(d13) = 62.84 r₂₅ = ∞ d₂₅ = 0.5000 r₂₆ = ∞ d₂₆ = 0.5000n_(d14) = 1.51633 ν_(d14) = 64.14 r₂₇ = ∞ d₂₇ = 1.3641 r₂₈ = ∞ (ImagePlane) Aspherical Coefficients 8th surface K = 1.5876 A₄ = 2.6616 × 10⁻⁴A₆ = 3.3939 × 10⁻⁶ A₈ = −1.0023 × 10⁻⁷ A₁₀ = 0 13th surface K = 0 A₄ =−2.7230 × 10⁻⁴ A₆ = −5.7432 × 10⁻⁶ A₈ = −3.4301 × 10⁻⁷ A₁₀ = 0 21thsurface K = 0 A₄ = −8.9975 × 10⁻⁴ A₆ = −1.8358 × 10⁻⁵ A₈ = 1.4143 × 10⁻⁶A₁₀ = 0 Zooming Data (∞) WE ST TE f (mm) 4.60758 7.85021 13.40785 FNO2.8000 3.4489 4.6187 2ω (°) 65.3 39.0 22.9 d₉ 14.75212 6.67783 2.00000d₁₂ 0.67500 4.26744 1.54139 d₂₀ 1.35767 6.03580 13.51290

EXAMPLE 4

r₁ = 29.0184 d₁ = 0.7437 n_(d1) = 1.80400 ν_(d1) = 46.57 r₂ = 7.3275 d₂= 1.3049 r₃ = ∞ d₃ = 4.0000 n_(d2) = 1.80400 ν_(d2) = 46.57 r₄ = ∞(Mirror) d₄ = 3.5133 n_(d3) = 1.80400 ν_(d3) = 46.57 r₅ = ∞ d₅ = 0.3000r₆ = −31.2038 d₆ = 0.7673 n_(d4) = 1.80400 ν_(d4) = 46.57 r₇ = 15.2085d₇ = 1.5760 r₈ = 33.1818 d₈ = 1.5628 n_(d5) = 1.84666 ν_(d5) = 23.78(Aspheric) r₉ = −29.4113 d₉ = (Variable) r₁₀ = ∞ (Stop) d₁₀ = 0.5000 r₁₁= 20.3172 d₁₁ = 1.9876 n_(d6) = 1.58913 ν_(d6) = 61.26 (Aspheric) r₁₂ =−14.3558 d₁₂ = 0.1387 r₁₃ = 7.0863 d₁₃ = 2.5021 n_(d7) = 1.48749 ν_(d7)= 70.23 r₁₄ = −521.1337 d₁₄ = 0.0001 r₁₅ = 217.6721 d₁₅ = 5.9501 n_(d8)= 1.84666 ν_(d8) = 23.78 r₁₆ = 4.5340 d₁₆ = (Variable) r₁₇ = 10.1062 d₁₇= 1.8686 n_(d9) = 1.60300 ν_(d9) = 65.44 r₁₈ = 46.5940 d₁₈ = (Variable)r₁₉ = −22.5387 d₁₉ = 2.3721 n_(d10) = 1.58913 ν_(d10) = 61.26 (Aspheric)r₂₀ = −5.8538 d₂₀ = 0.4297 r₂₁ = ∞ d₂₁ = 0.8000 n_(d11) = 1.51633ν_(d11) = 64.14 r₂₂ = ∞ d₂₂ = 0.8000 n_(d12) = 1.54771 ν_(d12) = 62.84r₂₃ = ∞ d₂₃ = 0.5000 r₂₄ = ∞ d₂₄ = 0.5000 n_(d13) = 1.51633 ν_(d13) =64.14 r₂₅ = ∞ d₂₅ = 1.3824 r₂₇ = ∞ (Image Plane) Aspherical Coefficients8th surface K = 1.9221 A₄ = 1.0674 × 10⁻⁴ A₆ = 7.5509 × 10⁻⁷ A₈ =−6.9692 × 10⁻⁸ A₁₀ = 0 11th surface K = 0 A₄ = −1.4582 × 10⁻⁴ A₆ =4.2034 × 10⁻⁸ A₆ = 1.1204 × 10⁻⁸ A₁₀ = 0 19th surface K = 0 A₄ = −1.8514× 10⁻³ A₆ = 6.5803 × 10⁻⁶ A₈ = −9.0686 × 10⁻⁷ A₁₀ = 0 Zooming Data (∞)WE ST TE f (mm) 4.65117 7.85007 13.29161 FNO 2.5000 3.4944 4.8337 2ω (°)68.4 41.7 24.7 d₉ 13.35295 7.17214 2.00000 d₁₆ 1.22323 4.89168 2.01917d₁₈ 0.94992 3.89804 12.56077

EXAMPLE 5

r₁ = 15.9959 d₁ = 2.0000 n_(d1) = 1.84666 ν_(d1) = 23.78 r₂ = 17.9366 d₂= 0.8000 (Aspheric) r₃ = 122.3665 d₃ = 1.0000 n_(d2) = 1.72916 ν_(d2) =54.68 r₄ = 6.1500 d₄ = 1.9000 r₅ = ∞ d₅ = 4.1000 n_(d3) = 1.56883 ν_(d3)= 56.36 r₆ = ∞ (Mirror) d₆ = 3.9000 n_(d4) = 1.56883 ν_(d4) = 56.36 r₇ =∞ d₇ = (Variable) r₈ = ∞ (Stop) d₈ = 0.5928 r₉ = 14.1418 d₉ = 3.0000n_(d5) = 1.80610 ν_(d5) = 40.92 (Aspheric) r₁₀ = −138.1914 d₁₀ =(Variable) r₁₁ = 9.2691 d₁₁ = 3.2000 n_(d6) = 1.48749 ν_(d6) = 70.23 r₁₂= −18.4588 d₁₂ = 1.0064 n_(d7) = 1.84666 ν_(d7) = 23.78 r₁₃ = 7.4386 d₁₃= 0.5000 r₁₄ = 9.1725 d₁₄ = 2.4000 n_(d8) = 1.80518 ν_(d8) = 25.42 r₁₅ =−16.4170 d₁₅ = (Variable) r₁₆ = 44.6119 d₁₆ = 0.8000 n_(d9) = 1.84666ν_(d9) = 23.78 r₁₇ = 8.9511 d₁₇ = (Variable) (Aspheric) r₁₈ = 11.2550d₁₈ = 2.6000 n_(d10) = 1.58913 ν_(d10) = 61.26 r₁₉ = 673.2282 d₁₉ =(Variable) (Aspheric) r₂₀ = ∞ d₂₀ = 1.5000 n_(d11) = 1.51633 ν_(d11) =64.14 r₂₁ = ∞ d₂₁ = 1.4400 n_(d12) = 1.54771 ν_(d12) = 62.84 r₂₂ = ∞ d₂₂= 0.8000 r₂₃ = ∞ d₂₃ = 0.8000 n_(d13) = 1.51633 ν_(d13) = 64.14 r₂₄ = ∞d₂₄ = 1.0000 r₂₅ = ∞ (Image Plane) Aspherical Coefficients 2nd surface K= 0 A₄ = −2.1855 × 10⁻⁴ A₆ = 3.4923 × 10⁻⁷ A₈ = 0 A₁₀ = 0 9th surface K= 5.1530 A₄ = −2.4340 × 10⁻⁴ A₆ = −7.4872 × 10⁻⁶ A₈ = 2.0515 × 10⁻⁷ A₁₀= −1.0188 × 10⁻⁸ 17th surface K = −3.7152 A₄ = 1.2209 × 10⁻³ A₆ =−1.7576 × 10⁻⁵ A₈ = 2.5810 × 10⁻⁶ A₁₀ = −1.2193 × 10⁻⁷ 19th surface K =1.4583 A₄ = −1.5578 × 10⁻⁴ A₆ = −1.1072 × 10⁻⁵ A₈ = 5.6481 × 10⁻⁷ A₁₀ =−8.6742 × 10⁻⁹ Zooming Data (∞) WE ST TE f (mm) 5.43000 10.6120015.80000 FNO 2.7116 3.7726 4.5293 2ω (°) 63.5 35.7 24.5 d₇ 13.124354.47821 0.50000 d₁₀ 0.81880 1.71785 0.50000 d₁₅ 0.60000 2.00387 4.09707d₁₇ 1.40000 8.20925 11.93740 d₁₉ 2.71758 2.25155 1.62627

EXAMPLE 6

r₁ = 49.3427 d₁ = 2.0000 n_(d1) = 1.84666 ν_(d1) = 23.78 r₂ = −115.4656d₂ = 0.4000 r₃ = −52.5304 d₃ = 1.0000 n_(d2) = 1.69350 ν_(d2) = 53.21(Aspheric) r₄ = 5.8428 d₄ = 1.8000 r₅ = ∞ d₅ = 4.0000 n_(d3) = 1.56883ν_(d3) = 56.36 r₆ = ∞ (Mirror) d₆ = 3.8000 n_(d4) = 1.56883 ν_(d4) =56.36 r₇ = ∞ d₇ = (Variable) r₈ = ∞ (Stop) d₈ = 0.6000 r₉ = 8.0295(Aspheric) d₉ = 2.8000 n_(d5) = 1.69350 ν_(d5) = 53.21 r₁₀ = −5.9145 d₁₀= 0.8000 n_(d6) = 1.80440 ν_(d6) = 39.59 r₁₁ = −12.3640 d₁₁ = (Variable)r₁₂ = 26.8805 d₁₂ = 0.8000 n_(d7) = 1.84666 ν_(d7) = 23.78 r₁₃ = 7.1849d₁₃ = (Variable) (Aspheric) r₁₄ = 10.7803 d₁₄ = 3.1000 n_(d8) = 1.48749ν_(d8) = 70.23 r₁₅ = −52.9481 d₁₅ = (Variable) r₁₆ = ∞ d₁₆ = 1.5000n_(d9) = 1.51633 ν_(d9) = 64.14 r₁₇ = ∞ d₁₇ = 1.4400 n_(d10) = 1.54771ν_(d10) = 62.84 r₁₈ = ∞ d₁₈ = 0.8000 r₁₉ = ∞ d₁₉ = 0.8000 n_(d11) =1.51633 ν_(d11) = 64.14 r₂₀ = ∞ d₂₀ = 1.0000 r₂₁ = ∞ (Image Plane)Aspherical Coefficients 3rd surface K = 0 A₄ = 2.6048 × 10⁻⁴ A₆ =−3.2365 × 10⁻⁶ A₈ = 2.2913 × 10⁻⁸ A₁₀ = 0 9th surface K = 0 A₄ = −3.0615× 10⁻⁴ A₆ = −2.0330 × 10⁻⁶ A₈ = −1.0403 × 10⁻⁷ A₁₀ = 0 13th surface K =−3.5241 A₄ = 1.8328 × 10⁻³ A₆ = −1.6164 × 10⁻⁵ A₈ = 3.5495 × 10⁻⁶ A₁₀ =−1.2410 × 10⁻⁷ Zooming Data (∞) WE ST TE f (mm) 5.38001 8.50001 13.45001FNO 3.0358 3.8702 4.5606 2ω (°) 65.8 43.8 28.4 d₇ 11.53527 6.152900.50000 d₁₁ 2.10162 2.49863 3.68430 d₁₃ 3.96820 9.09478 10.56416 d₁₅1.75491 1.61369 4.61155

EXAMPLE 7

r₁ = 21.0760 d₁ = 1.4000 n_(d1) = 1.74320 ν_(d1) = 49.34 r₂ = 7.9352(Aspheric) d₂ = 2.8000 r₃ = ∞ d₃ = 6.5000 n_(d2) = 1.56883 ν_(d2) =56.36 r₄ = ∞ (Mirror) d₄ = 6.0000 n_(d3) = 1.56883 ν_(d3) = 56.36 r₅ = ∞d₅ = 0.8000 r₆ = −18.8610 d₆ = 0.8000 n_(d4) = 1.72916 ν_(d4) = 54.68 r₇= 29.7460 d₇ = 0.5273 r₈ = 25.1850 d₈ = 1.9000 n_(d5) = 1.84666 ν_(d5) =23.78 r₉ = −121.8149 d₉ = (Variable) r₁₀ = ∞ (Stop) d₁₀ = 0.8000 r₁₁ =11.8772 d₁₁ = 1.9992 n_(d6) = 1.49700 ν_(d6) = 81.54 (Aspheric) r₁₂ =−22.2117 d₁₂ = 0.3000 r₁₃ = 8.0295 d₁₃ = 1.9997 r_(d7) = 1.48749 ν_(d7)= 70.23 r₁₄ = −16.2855 d₁₄ = 0.7997 n_(d8) = 1.64769 ν_(d8) = 33.79 r₁₅= −52.6732 d₁₅ = 0.3000 r₁₆ = 7.3242 d₁₆ = 1.3308 n_(d9) = 1.84666ν_(d9) = 23.78 r₁₇ = 4.4772 d₁₇ = 1.2000 r₁₈ = 17.2769 d₁₈ = 1.1317n_(d10) = 1.80610 ν_(d10) = 40.92 r₁₉ = 6.2199 d₁₉ = (Variable) r₂₀ =9.0812 d₂₀ = 2.0000 n_(d11) = 1.61800 ν_(d11) = 63.33 r₂₁ = 19.8406 d₂₁= (Variable) r₂₂ = −34.2139 d₂₂ = 2.0000 n_(d12) = 1.58313 ν_(d12) =59.38 (Aspheric) r₂₃ = −9.7728 d₂₃ = 1.0032 r₂₄ = ∞ d₂₅ = 1.4400 n_(d13)= 1.54771 ν_(d13) = 62.84 r₂₅ = ∞ d₂₆ = 0.8000 r₂₆ = ∞ d₂₇ = 0.8000n_(d14) = 1.51633 ν_(d14) = 64.14 r₂₇ = ∞ d₂₈ = 1.0003 r₂₈ = ∞ (ImagePlane) Aspherical Coefficients 2nd surface K = 0 A₄ = −9.3483 × 10⁻⁵ A₆= 1.4787 × 10⁻⁷ A₈ = −4.5620 × 10⁻⁸ A₁₀ = 0 11th surface K = 0 A₄ =−2.6863 × 10⁻⁴ A₆ = −1.0879 × 10⁻⁷ A₈ = 3.8711 × 10⁻⁹ A₁₀ ₌ ₀ 22ndsurface K = 0 A₄ = −4.8081 × 10⁻⁴ A₆ = 5.9535 × 10⁻⁶ A₈ = −1.6767 × 10⁻⁷A₁₀ = 0 Zooming Data (∞) WE ST TE f (mm) 5.80000 9.17005 14.49992 FNO2.6880 3.4974 4.5402 2ω (°) 60.8 40.1 25.4 d₉ 14.10553 7.78994 2.48873d₁₉ 1.54225 5.16705 2.56297 d₂₁ 2.32790 5.01801 12.92472

EXAMPLE 8

r₁ = 16.1825 d₁ = 1.4000 n_(d1) = 1.80610 ν_(d1) = 40.92 (Aspheric) r₂ =7.3872 d₂ = 3.5000 r₃ = ∞ d₃ = 6.5000 n_(d2) = 1.60311 ν_(d2) = 60.64 r₄= ∞ (Mirror) d₄ = 6.0000 n_(d3) = 1.60311 ν_(d3) = 60.64 r₅ = ∞ d₅ =0.7950 r₆ = −27.1461 d₆ = 0.8000 n_(d4) = 1.72916 ν_(d4) = 54.68 r₇ =20.2982 d₇ = 0.5273 r₈ = 17.2255 d₈ = 1.9000 n_(d5) = 1.84666 ν_(d5) =23.78 r₉ = 90.2451 d₉ = (Variable) r₁₀ = ∞ (Stop) d₁₀ = 0.8000 r₁₁ =17.0416 d₁₁ = 1.9965 n_(d6) = 1.56384 ν_(d6) = 60.67 (Aspheric) r₁₂ =−13.7245 d₁₂ = 0.5000 r₁₃ = 5.5039 d₁₃ = 3.7857 n_(d7) = 1.48749 ν_(d7)= 70.23 r₁₄ = −38.8943 d₁₄ = 0.8000 n_(d8) = 1.69895 ν_(d8) = 30.13 r₁₅= 4.2611 d₁₅ = (Variable) r₁₆ = 16.8715 d₁₆ = 2.0000 n_(d9) = 1.48749ν_(d9) = 70.23 r₁₇ = 96.4706 d₁₇ = (Variable) r₁₈ = −60.1937 d₁₈ =2.0000 n_(d10) = 1.56384 ν_(d10) = 60.67 r₁₉ = −11.5463 d₁₉ = 1.0039(Aspheric) r₂₀ = ∞ d₂₀ = 1.4400 n_(d11) = 1.54771 ν_(d11) = 62.84 r₂₁ =∞ d₂₁ = 0.8000 r₂₂ = ∞ d₂₂ = 0.8000 n_(d12) = 1.51633 ν_(d12) = 64.14r₂₃ = ∞ d₂₃ = 1.0021 r₂₄ = ∞ (Image Plane) Aspherical Coefficients 1stsurface K = 0 A₄ = 5.1308 × 10⁻⁵ A₆ = 2.3428 × 10⁻⁷ A₈ = −3.7916 × 10⁻⁹A₁₀ = 7.2819 × 10⁻¹¹ 11th surface K = 0 A₄ = −1.6960 × 10⁻⁴ A₆ = −1.0587× 10⁻⁶ A₈ = 5.6885 × 10⁻⁸ A₁₀ = −2.0816 × 10⁻¹⁰ 19th surface K = 0 A₄ =2.9238 × 10⁻⁴ A₆ = −1.4179 × 10⁻⁵ A₈ = 6.7945 × 10⁻⁷ A₁₀ = −1.6439 ×10⁻⁸ Zooming Data (∞) WE ST TE f (mm) 5.80001 9.17026 14.49938 FNO2.6926 3.5230 4.5194 2ω (°) 61.1 40.1 25.7 d₉ 14.09978 8.00554 2.48873d₁₅ 2.47558 7.50212 3.24411 d₁₇ 3.07729 4.13993 13.92316

EXAMPLE 9

r₁ = 21.2658 d₁ = 1.0000 n_(d1) = 1.74100 ν_(d1) = 52.64 r₂ = 8.6245 d₂= 3.3711 r₃ = ∞ d₃ = 5.8400 n_(d2) = 1.80400 ν_(d2) = 46.57 r₄ = ∞(Mirror) d₄ = 5.4952 n_(d3) = 1.80400 ν_(d3) = 46.57 r₅ = ∞ d₅ = 0.3221r₆ = 300.0000 d₆ = 1.0000 n_(d4) = 1.74320 ν_(d4) = 49.34 r₇ = 15.3314d₇ = 0.5979 (Aspheric) r₈ = 15.8974 d₈ = 1.4903 n_(d5) = 1.84666 ν_(d5)= 23.78 r₉ = 43.0822 d₉ = (Variable) r₁₀ = ∞ (Stop) d₁₀ = 0.6000 r₁₁ =63.9771 d₁₁ = 1.3913 n_(d6) = 1.61800 ν_(d6) = 63.33 r₁₂ = −23.2380 d₁₂= (Variable) r₁₃ = 7.9674 d₁₃ = 2.3478 n_(d7) = 1.48749 ν_(d7) = 70.23(Aspheric) r₁₄ = −68.3182 d₁₄ = 0.1000 r₁₅ = 24.3652 d₁₅ = 3.3012 n_(d8)= 1.84666 ν_(d8) = 23.78 r₁₆ = 7.7880 d₁₆ = 0.2484 r₁₇ = 9.2912 d₁₇ =2.1349 n_(d9) = 1.72916 ν_(d9) = 54.68 r₁₈ = −19.4929 d₁₈ = 0.7000n_(d10) = 1.53172 ν_(d10) = 48.84 r₁₉ = 5.2999 d₁₉ = (Variable) r₂₀ =−22.5496 d₂₀ = 2.5068 n_(d11) = 1.58913 ν_(d11) = 61.14 (Aspheric) r₂₁ =−6.5395 d₂₁ = 1.0000 r₂₂ = ∞ d₂₂ = 1.5000 n_(d12) = 1.51633 ν_(d12) =64.14 r₂₃ = ∞ d₂₃ = 1.4400 n_(d13) = 1.54771 ν_(d13) = 62.84 r₂₄ = ∞ d₂₄= 0.8000 r₂₅ = ∞ d₂₅ = 0.8000 n_(d14) = 1.51633 ν_(d14) = 64.14 r₂₆ = ∞d₂₆ = 1.0894 r₂₇ = ∞ (Image Plane) Aspherical Coefficients 7th surface K= 0 A₄ = −6.9423 × 10⁻⁵ A₆ = 1.9216 × 10⁻⁷ A₈ = −2.3395 × 10⁻⁸ A₁₀ = 013th surface K = 0 A₄ = −2.1881 × 10⁻⁴ A₆ = −2.0288 × 10⁻⁶ A₈ = 7.6472 ×10⁻¹⁰ A₁₀ = 0 20th surface K = 0 A₄ = −1.0095 × 10⁻³ A₆ = 3.4022 × 10⁻⁸A₈ = −1.7165 × 10⁻⁷ A₁₀ = 0 Zooming Data (∞) WE ST TE f (mm) 5.521797.96811 15.98093 FNO 2.4770 2.9873 4.5000 2ω (°) 64.5 44.7 22.7 d₉17.73448 10.81643 2.00000 d₁₂ 1.20000 3.80000 3.50000 d₁₉ 2.603005.58623 15.86209

EXAMPLE 10

r₁ = 24.8917 d₁ = 1.0000 n_(d1) = 1.74100 ν_(d1) = 52.64 r₂ = 8.0792 d₂= 2.3760 r₃ = ∞ d₃ = 5.2400 n_(d2) = 1.80400 ν_(d2) = 46.57 r₄ = ∞(Mirror) d₄ = 5.0006 n_(d3) = 1.80400 ν_(d3) = 46.57 r₅ = ∞ d₅ = 0.2922r₆ = 300.0000 d₆ = 1.0000 n_(d4) = 1.74320 ν_(d4) = 49.34 r₇ = 14.5213d₇ = 0.1000 (Aspheric) r₈ = 14.5896 d₈ = 1.7517 n_(d5) = 1.84666 ν_(d5)= 23.78 r₉ = 64.9869 d₉ = (Variable) r₁₀ = ∞ (Stop) d₁₀ = 0.60000 r₁₁ =33.4595 d₁₁ = 1.8985 n_(d6) = 1.61800 ν_(d6) = 63.33 r₁₂ = −11.1499 d₁₂= 0.7000 n_(d7) = 1.80518 ν_(d7) = 25.42 r₁₃ = −20.0542 d₁₃ = (Variable)r₁₄ = 10.2987 d₁₄ = 2.0299 n_(d8) = 1.48749 ν_(d8) = 70.23 (Aspheric)r₁₅ = 18890.0000 d₁₅ = 0.1000 r₁₆ = 19.8062 d₁₆ = 4.5045 n_(d9) =1.84666 ν_(d9) = 23.78 r₁₇ = 9.7836 d₁₇ = 0.2000 r₁₈ = 11.2175 d₁₈ =1.7598 n_(d10) = 1.72916 ν_(d10) = 54.68 r₁₉ = −51.5183 d₁₉ = 0.7000n_(d11) = 1.53172 ν_(d11) = 48.84 r₂₀ = 5.5430 d₂₀ = (Variable) r₂₁ =−23.0137 d₂₁ = 1.9685 n_(d12) = 1.58913 ν_(d12) = 61.14 (Aspheric) r₂₂ =−7.0933 d₂₂ = 1.0000 r₂₃ = ∞ d₂₃ = 1.5000 n_(d13) = 1.51633 ν_(d13) =64.14 r₂₄ = ∞ d₂₄ = 1.4400 n_(d14) = 1.54771 ν_(d14) = 62.84 r₂₅ = ∞ d₁₅= 0.8000 r₂₆ = ∞ d₁₆ = 0.8000 n_(d15) = 1.51633 ν_(d15) = 64.14 r₂₇ = ∞d₁₇ = 1.0106 r₂₈ = ∞ (Image Plane) Aspherical Coefficients 7th surface K= 0 A₄ = −8.0580 × 10⁻⁵ A₆ = 7.6927 × 10⁻⁷ A₈ = −2.7173 × 10⁻⁸ A₁₀ = 014th surface K = 0 A₄ = −1.1033 × 10⁻⁴ A₆ = −1.4285 × 10⁻⁸ A₈ = −1.8629× 10⁻⁸ A₁₀ = 0 21st surface K = 0 A₄ = −8.5891 × 10⁻⁴ A₆ = 1.0215 × 10⁻⁵A₈ = −3.2143 × 10⁻⁷ A₁₀ = 0 Zooming Data (∞) WE ST TE f (mm) 5.868799.99877 17.39648 FNO 2.4340 3.2140 4.5000 2ω (°) 61.4 35.8 21.0 d₉17.88781 8.41716 2.00000 d₁₃ 1.20000 6.81663 3.50000 d₂₀ 3.14136 7.0123116.74709

EXAMPLE 11

r₁ = 41.9739 d₁ = 1.2000 n_(d1) = 1.77250 ν_(d1) = 49.60 r₂ = 11.1642 d₂= 2.9000 r₃ = ∞ d₃ = 6.5000 n_(d2) = 1.78590 ν_(d2) = 44.20 r₄ = ∞(Mirror) d₄ = 6.0000 n_(d3) = 1.78590 ν_(d3) = 44.20 r₅ = ∞ d₅ = 0.3971r₆ = 28.0000 d₆ = 1.2000 n_(d4) = 1.74330 ν_(d4) = 49.33 r₇ = 11.3578 d₇= 0.3457 (Aspheric) r₈ = 9.4845 d₈ = 1.7925 n_(d5) = 1.84666 ν_(d5) =23.78 r₉ = 14.2959 d₉ = (Variable) r₁₀ = ∞ (Stop) d₁₀ = 1.0000 r₁₁ =47.8757 d₁₁ = 1.9600 n_(d6) = 1.72916 ν_(d6) = 54.68 r₁₂ = −9.0806 d₁₂ =0.7000 n_(d7) = 1.72825 ν_(d7) = 28.46 r₁₃ = −25.4395 d₁₃ = (Variable)r₁₄ = 9.1761 d₁₄ = 1.9500 n_(d8) = 1.74330 ν_(d8) = 49.33 (Aspheric) r₁₅= 75.3616 d₁₅ = 0.8461 r₁₆ = 24.3002 d₁₆ = 3.8969 n_(d9) = 1.74330ν_(d9) = 49.33 r₁₇ = ∞ d₁₇ = 1.0000 n_(d10) = 1.72825 ν_(d10) = 28.46r₁₈ = 4.8249 d₁₈ = (Variable) r₁₉ = 49.5382 d₁₉ = 2.7500 n_(d11) =1.69350 ν_(d11) = 53.20 r₂₀ = −10.0407 d₂₀ = 0.8269 (Aspheric) r₂₁ = ∞d₂₁ = 1.4400 n_(d12) = 1.54771 ν_(d12) = 62.84 r₂₂ = ∞ d₂₂ = 0.8000 r₂₃= ∞ d₂₃ = 0.8000 n_(d13) = 1.51633 ν_(d13) = 64.14 r₂₄ = ∞ d₂₄ = 1.0447r₂₅ = ∞ (Image Plane) Aspherical Coefficients 7th surface K = 0 A₄ =2.2504 × 10⁻⁵ A₆ = 2.6875 × 10⁻⁶ A₈ = −1.2962 × 10⁻⁷ A₁₀ = 2.8718 × 10⁻⁹14th surface K = 0 A₄ = −9.8664 × 10⁻⁵ A₆ = 4.0400 × 10⁻⁶ A₈ = −4.4986 ×10⁻⁷ A₁₀ = 1.3851 × 10⁻⁸ 20th surface K = 0 A₄ = 5.3089 × 10⁻⁴ A₆ =−1.6198 × 10⁻⁵ A₈ = 4.4581 × 10⁻⁷ A₁₀ = −4.9080 × 10⁻⁹ Zooming Data (∞)WE ST TE f (mm) 6.02622 9.31725 14.28897 FNO 2.7652 3.4888 4.5271 2ω (°)62.4 42.8 28.7 d₉ 14.24100 6.97804 2.00694 d₁₃ 2.10000 6.51339 5.34809d₁₈ 2.46549 5.31403 11.45279

EXAMPLE 12

r₁ = −14.2761 d₁ = 5.1000 n_(d1) = 1.50913 ν_(d1) = 56.20 (Aspheric) r₂= ∞ (Mirror) d₂ = 5.7941 n_(d2) = 1.50913 ν_(d2) = 56.20 r₃ = ∞ d₃ =2.1000 r₄ = −6.4892 d₄ = 0.8000 n_(d3) = 1.64000 ν_(d3) = 60.07 r₅ =−84.1654 d₅ = 1.1935 n_(d4) = 1.84666 ν_(d4) = 23.78 r₆ = −16.8306 d₆ =(Variable) r₇ = ∞ (Stop) d₇ = 0.4000 r₈ = 34.9225 d₈ = 1.4006 n_(d5) =1.74330 ν_(d5) = 49.33 (Aspheric) r₉ = −15.2934 d₉ = 0.1500 r₁₀ = 6.1210d₁₀ = 3.3481 n_(d6) = 1.61800 ν_(d6) = 63.33 r₁₁ = 27.4556 d₁₁ = 0.8000n_(d7) = 1.84666 ν_(d7) = 23.78 r₁₂ = 4.9467 d₁₂ = (Variable) r₁₃ =13.6380 d₁₃ = 1.4415 n_(d8) = 1.51633 ν_(d8) = 64.14 r₁₄ = −143.7586 d₁₄= (Variable) r₁₅ = −19.5436 d₁₅ = 1.3641 n_(d9) = 1.58913 ν_(d9) = 61.25r₁₆ = −7.1346 d₁₆ = 0.8000 (Aspheric) r₁₇ = ∞ d₁₇ = 1.0500 n_(d10) =1.54771 ν_(d10) = 62.84 r₁₈ = ∞ d₁₈ = 0.8000 r₁₉ = ∞ d₁₉ = 0.8000n_(d11) = 1.51633 ν_(d11) = 64.14 r₂₀ = ∞ d₂₀ = 0.9669 r₂₁ = ∞ (ImagePlane) Aspherical Coefficients 1st surface K = 0 A₄ = 3.2165 × 10⁻⁴ A₆ =−9.1756 × 10⁻⁷ A₈ = 4.1788 × 10⁻⁹ A₁₀ = 0.0000 8th surface K = 0 A₄ =−1.2083 × 10⁻⁴ A₆ = 1.1516 × 10⁻⁷ A₈ = −2.9381 × 10⁻⁸ A₁₀ = 0.0000 16thsurface K = 0 A₄ = 1.3137 × 10⁻³ A₆ = −2.0878 × 10⁻⁵ A₈ = 4.9397 × 10⁻⁷A₁₀ = 0.0000 Zooming Data (∞) WE ST TE f (mm) 5.02898 8.69474 14.52092FNO 2.6544 3.5217 4.5079 2ω (°) 64.8 38.2 22.6 d₆ 14.61860 7.392511.80000 d₁₂ 3.75585 8.20107 4.39975 d₁₄ 3.16733 5.96897 15.38987

Aberration diagrams for Example 1 and Example 2 upon focused on anobject point at infinity are shown in FIG. 13 and FIG. 14, respectively.In these aberration diagrams, spherical aberrations SA, astigmatisms AS,distortions DT and chromatic aberrations of magnification CC areillustrated at the wide-angle end (a), intermediate or standard state(b) and telephoto end (c).

Enumerated below are the values of L, d/L, D_(FT)/f_(T), M₃/M₂, f₁₁/f₁₂,β_(Rt), a, and t_(LPF) concerning conditions (a) to (f) in the aforesaidexamples.

Ex. L d/L D_(FT)/f_(T) M₃/M₂ f₁₁/f₁₂ 1 5.6 0.72088 0.78471 1.19347−0.12343 2 6.0 0.79009 0.76004 0.53348 −0.32094 3 5.6 0.71748 0.114960.93206 0.36284 4 6.0 0.69413 0.15191 0.92989 0.20195 5 6.64 0.767970.25931 3rd-negative 0 6 6.64 0.74877 0.27393 3rd-negative 0 7 6.641.19996 0.17676 0.91213 0.37232 8 6.64 1.17430 0.22374 0.93381 0.39484 96.64 0.94629 0.21901 0.85382 0.22917 10 6.64 0.85491 0.20119 0.855230.05553 11 6.64 0.94867 0.37452 0.73366 0.09671 12 6.0 1.20313 0.303010.95350 1.26698 Ex. β_(Rt) a t_(LPF) 1 −1.6884 3.0 1.80 2 −1.19598 3.01.80 3 −1.49396 3.0 1.80 4 −1.26884 3.0 0.80 5 −1.51672 3.0 1.55 6−1.38530 3.0 1.44 7 −1.26560 3.0 1.44 8 −1.30121 3.0 1.44 9 −1.05735 3.01.44 10  −1.14882 3.0 1.44 11  −0.86588 3.0 1.44 12  −1.36309 2.5 1.20

How to receive the inventive optical path-bending zoom optical system inplace is now explained specifically. FIGS. 15( a) and 15(b) areillustrative of how to receive the optical path-bending zoom opticalsystem of FIG. 9 (Example 9) in place. FIG. 15( b) is a sectionalschematic inclusive of an optical path-bending axis, showing Example 9of the optical path-bending zoom optical system at the wide-angle end.In this state, two lenses forming the second lens group G2 and theoptical path-bending prism P forming a part of the 1-1st lens group G1-1are relocated in a space between the 1-2nd lens group G1-2 and thesecond lens group G2, and the negative meniscus lens L1 located in frontof the optical path-bending prism P in the 1-1st lens group G1-1 isreceived in the resulting space, so that the thickness of the opticalpath-bending zoom optical system in its entrance axis direction (in thedepth direction of the camera) can be reduced. It is here noted thatwhen there is a space on the image plane I side with respect to thesecond lens group G2, it is preferable to relocate the opticalpath-bending prism P and the 1-2nd lens group G1-2 as well as the secondlens group G2, etc. on the image plane I side.

FIG. 16 is a conceptual schematic of one embodiment of how to receivethe optical path-bending zoom optical system in place when thereflecting optical element is constructed of a mirror M. The mirror M istilted at a position indicated by a broken line, and lenses L2 and L3located on the image plane I side with respect to the mirror M aretilted at positions indicated by broken lines, so that the thickness ofthe zoom optical system in its optical axis direction (in the depthdirection of a camera) can be reduced.

FIG. 17 is a conceptual schematic of another embodiment of how toreceive the optical path-bending zoom optical system in place when thereflecting optical element is formed of a mirror M. The mirror M istilted at a position indicated by a broken line and a lens group LGlocated on the object side with respect to the mirror M is received inthe resulting space, thereby achieving similar thickness reductions.Instead of tilting the mirror M, it may be relocated along the opticalaxis after bending, as shown in FIG. 15.

FIGS. 18( a) and 18(b) are illustrative of one embodiment of thereflecting optical element for bending an optical path, which isconstructed of a liquid or transformable prism LP (see FIG. 18( a)).This reflecting optical element may be received in place as by removingthe liquid therefrom as shown in FIG. 18( b), thereby achievingthickness reductions. Alternatively, lens groups located on the objectside with respect to the prism LP may be received in the resulting space(see FIG. 17), or other lenses may be tilted (see FIG. 16), againachieving thickness reductions.

In the optical path-bending zoom optical system of the presentinvention, the reflecting optical element for bending an optical pathmay also be constructed of a variable-shape mirror. The variable-shapemirror is a reflecting mirror comprising a transformable film with areflecting mirror coating applied thereon. This reflecting mirror may berelocated by folding or winding.

When the reflecting optical element for bending an optical path isconstructed of a variable-shape mirror, it is acceptable to carry outfocusing by the transformation of that mirror, as shown conceptually inFIG. 19. For focusing on a nearby object, only the transformation of aplanar form of variable-shape mirror DM into a concave surface is neededupon focused on a point at infinity, as shown by an arrow. That is, forfocusing on a nearby object, the surface shape of the variable-shapemirror DM is transformed into an aspheric surface shape within aneffective reflecting surface area. Especially when power is imparted toa reflecting surface that is of rotationally symmetric shape,decentration aberrations are produced at that surface due to decenteredincidence of light thereon. It is thus desired that the variable-shapemirror DM be defined by a rotationally asymmetric curved surface.

Off-axis, rotationally asymmetric distortions or the like, too, areproduced by decentration. To make correction for decentrationaberrations symmetric with respect to plane, it is preferable totransform the surface of the variable-shape mirror DM into a curvedsurface with respect to plane, where only one symmetric surface isdefined by a plane including an optical axis entered in and reflected atthe reflecting surface of the variable-shape mirror DM, as shown in FIG.20.

Referring again to FIG. 19, the variable-shape mirror DM takes a planarform upon focused on a point at infinity. To make correction fordecentration aberrations produced upon focused on a nearby object point,however, it is preferable to transform the reflecting surface of themirror DM into a rotationally asymmetric surface having only onesymmetric plane, as shown in FIG. 20. With this arrangement, it ispossible to achieve the size reduction of the whole of an electronicimage pickup system and maintain its performance.

FIG. 21 is illustrative of one embodiment of how to correct cameramovements by tilting the reflecting surface of a variable-shape mirrorDM in an arrow direction. In the state of FIG. 19, there is no cameramovement, and in the state of FIG. 21, the function of correcting cameramovements by tilting the reflecting surface of the variable-shape mirrorDM is brought into action. When an image pickup device turns down withrespect to a phototaking direction as shown in FIG. 21, the inclinationof the reflecting surface of the variable-shape mirror DM displaces froma broken-line position to a solid-line position so that the entranceoptical axis is kept from inclination. Preferably in this case, thewhole surface shape of the variable-shape mirror DM is so transformedthat fluctuations of aberrations can be prevented.

In the present invention, it is acceptable to impart power thereflecting surface of the reflecting optical element for bending anoptical path and configure its surface shape with a free-form surface orthe like. Alternatively, it is acceptable to construct the reflectingsurface of the reflecting optical element with a holographic opticalelement (HOE).

When the reflecting optical element is constructed of an opticalpath-bending prism P as set forth in Examples 1 to 12, it is acceptableto cement the prism P to lenses located before and after the same.

When an electronic image pickup system such as a digital camera isconstructed using the optical path-bending zoom optical system of thepresent invention, it is acceptable to interpose an optical pathsplitter element between the optical path-bending zoom optical systemand an electronic image pickup device such as a CCD to split anphototaking optical path to a finder optical path, as shown in FIG. 22.FIG. 22 is a front view of a digital camera 40 in this case, an opticalpath-bending zoom optical system comprises a reflecting optical elementM1 for bending an optical path through 90° and a lens group LA locatedon the image plane side of the element M1, with an image pickup deviceCCD 49 positioned on the image plane. Between the lens group LA and CCD49, there is interposed an optical path splitter element M2 such as ahalf-silvered mirror to split the optical path, so that a part thereofis deflected to a side substantially vertical to a plane including anoptical axis before and after reflection at the reflecting opticalelement M1 (the upper side of FIG. 22). It is understood that theoptical path splitter element M2 may be defined by a reflecting surfacethat is inserted only when a light beam is guided to the finder opticalpath. An optical path reflected at the optical path splitter element M2is bent by another reflecting surface M3 through 90° in a planeincluding an optical axis before and after reflected at the optical pathsplitter element M2 and further bent by a fourth reflecting surface M4through 90°, running substantially parallel with the optical axisentered in the reflecting optical element M1. Although an eyepieceoptical system is not shown in FIG. 22, it is understood that it islocated on the exit side of the fourth reflecting surface M4 or beforeand after a plane including that reflecting surface M4, so that asubject image under observation is viewed by the viewer's eyeballpositioned on the exit side of the fourth reflecting surface M4.

Throughout Examples 1 to 12, the low-pass filter LF is constructed ofthree filter elements one upon another. However, it is appreciated thatmany modifications may be made to the aforesaid examples withoutdeparting from the scope of the invention. For instance, the low-passfilter may be formed of one single low-pass filter element.

In each of the aforesaid examples, the final lens group is provided onits image side with a near-infrared cut filter IF or a low-pass filterLF having a near-infrared sharp cut coat surface IC on its entrancesurface side. This near-infrared cut filter IF or near-infrared sharpcut coat surface IC is designed to have a transmittance of at least 80%at 600 nm wavelength and a transmittance of up to 10% at 700 nmwavelength. More specifically, the low-pass filter has a multilayerstructure made up of such 27 layers as mentioned below; however, thedesign wavelength is 780 nm.

Physical Thickness Substrate Material (nm) λ/4  1st layer Al₂O₃ 58.960.50  2nd layer TiO₂ 84.19 1.00  3rd layer SiO₂ 134.14 1.00  4th layerTiO₂ 84.19 1.00  5th layer SiO₂ 134.14 1.00  6th layer TiO₂ 84.19 1.00 7th layer SiO₂ 134.14 1.00  8th layer TiO₂ 84.19 1.00  9th layer SiO₂134.14 1.00 10th layer TiO₂ 84.19 1.00 11th layer SiO₂ 134.14 1.00 12thlayer TiO₂ 84.19 1.00 13th layer SiO₂ 134.14 1.00 14th layer TiO₂ 84.191.00 15th layer SiO₂ 178.41 1.33 16th layer TiO₂ 101.03 1.21 17th layerSiO₂ 167.67 1.25 18th layer TiO₂ 96.82 1.15 19th layer SiO₂ 147.55 1.0520th layer TiO₂ 84.19 1.00 21st layer SiO₂ 160.97 1.20 22nd layer TiO₂84.19 1.00 23rd layer SiO₂ 154.26 1.15 24th layer TiO₂ 95.13 1.13 25thlayer SiO₂ 160.97 1.20 26th layer TiO₂ 99.34 1.18 27th layer SiO₂ 87.190.65 Air

The aforesaid near-infrared sharp cut coat has such transmittancecharacteristics as shown in FIG. 23.

The low-pass filter LF is provided on its exit surface side with a colorfilter or coat for reducing the transmission of colors at such a shortwavelength band as shown in FIG. 24, thereby enhancing the colorreproducibility of electronic images.

Preferably, such a filter or coat should be such that the ratio of thetransmittance of 420 nm wavelength with respect to the transmittance ofa wavelength in the range of 400 nm to 700 nm at which the highesttransmittance is found is at least 15% and that the ratio of 400 nmwavelength with respect to the highest wavelength transmittance is up to6%.

It is thus possible to reduce a discernible difference between thecolors perceived by the human eyes and the colors of the image to bepicked up and reproduced. In other words, it is possible to preventdegradation in images due to the fact that a color of short wavelengthless likely to be perceived through the human sense of sight can bereadily seen by the human eyes.

When the ratio of the 400 nm wavelength transmittance is greater than6%, the short wavelength region less likely to be perceived by the humaneyes would be reproduced with perceivable wavelengths. When the ratio ofthe 420 nm wavelength transmittance is less than 15%, a wavelengthregion perceivable by the human eyes is less likely to be reproduced,putting colors in an ill-balanced state.

Such means for limiting wavelengths can be more effective for imagepickup systems using a complementary mosaic filter.

In each of the aforesaid examples, coating is applied in such a waythat, as shown in FIG. 24, the transmittance for 400 nm wavelength is0%, the transmittance for 420 nm is 90%, and the transmittance for 440nm peaks or reaches 100%.

With the synergistic action of the aforesaid near-infrared sharp cutcoat and that coating, the transmittance for 400 nm is set at 0%, thetransmittance for 420 nm at 80%, the transmittance for 600 nm at 82%,and the transmittance for 700 nm at 2% with the transmittance for 450 nmwavelength peaking at 99%, thereby ensuring more faithful colorreproduction.

The low-pass filter LF is made up of three different filter elementsstacked one upon another in the optical axis direction, each filterelement having crystallographic axes in directions where, upon projectedonto the image plane, the azimuth angle is horizontal (=0°) and ±45°therefrom. Three such filter elements are mutually displaced by a μm inthe horizontal direction and by SQRT(1/2)×a in the ±45° direction forthe purpose of moiré control, wherein SQRT means a square root asalready mentioned.

The image pickup plane I of a CCD is provided thereon with acomplementary mosaic filter wherein, as shown in FIG. 25, color filterelements of four colors, cyan, magenta, yellow and green are arranged ina mosaic fashion corresponding to image pickup pixels. Morespecifically, these four different color filter elements, used in almostequal numbers, are arranged in such a mosaic fashion that neighboringpixels do not correspond to the same type of color filter elements,thereby ensuring more faithful color reproduction.

To be more specific, the complementary mosaic filter is composed of atleast four different color filter elements, as shown in FIG. 25, whichshould preferably have such characteristics as given below.

Each green color filter element G has a spectral strength peak at awavelength G_(P), each yellow filter element Ye has a spectral strengthpeak at a wavelength Y_(P), each cyan filter element C has a spectralstrength peak at a wavelength C_(P), and each magenta filter element Mhas spectral strength peaks at wavelengths M_(P1) and M_(P2), and thesewavelengths satisfy the following conditions.

510 nm<G_(P)<540 nm

5 nm<Y _(P) −G _(P)<35 nm

−100 nm<C _(P) −G _(P)<−5 nm

430 nm<M_(P1)<480 nm

580 nm<M_(P2)<640 nm

To ensure higher color reproducibility, it is preferred that the green,yellow and cyan filter elements have a strength of at least 80% at 530nm wavelength with respect to their respective spectral strength peaks,and the magenta filter elements have a strength of 10% to 50% at 530 nmwavelength with their spectral strength peak.

One example of the wavelength characteristics in the aforesaidrespective examples is shown in FIG. 26. The green filter element G hasa spectral strength peak at 525 nm. The yellow filter element Ye has aspectral strength peak at 555 nm. The cyan filter element C has aspectral strength peak at 510 nm. The magenta filter element M has peaksat 445 nm and 620 nm. At 530 nm, the respective color filter elementshave, with respect to their respective spectral strength peaks,strengths of 99% for G, 95% for Ye, 97% for C and 38% for M.

For such a complementary filter, such signal processing as mentionedbelow is electrically carried out by means of a controller (not shown)(or a controller used with digital cameras).

For luminance signals,

Y=|G+M+Ye+C|×1/4

For chromatic signals,

R−Y=|(M+Ye)−(G+C)|

B−Y=|(M+C)−(G+Ye)|

Through this signal processing, the signals from the complementaryfilter are converted into R (red), G (green) and B (blue) signals.

In this regard, it is noted that the aforesaid near-infrared sharp cutcoat may be located anywhere on the optical path, and that the number oflow-pass filters F may be either two as mentioned above or one.

One typical detailed aperture stop portion in each example is shown inFIG. 27. At the stop position on the optical axis between the first lensgroup G1 and the second lens group G2 forming part of the image pickupoptical system, there is located a turret 10 capable of makingfive-stage brightness adjustments at 0, −1, −2, −3 and −4 stages. Theturret 10 is provided with a 0 stage adjustment opening 1A having afixed circular aperture shape of about 4 mm in diameter (which has a 550nm wavelength transmittance of 100%), a −1 stage correction opening 1Bhaving an aperture area about half that of the opening 1A and a fixedaperture shape and comprising a transparent plane-parallel plate (havinga 550 nm wavelength transmittance of 99%) and −2, −3, −4 stagecorrection openings 1C, 1D and 1E provided with ND filters having a 550nm wavelength transmittance of 50%, 25% and 13%, respectively.

The turret 10 is rotated around its rotating shaft 11 to locate any oneof the openings at the stop position for light quantity adjustments.

In the opening, there is also located an ND filter designed to have a550 nm wavelength transmittance of less than 80% when the effectiveF-number or F_(no)′ is F_(no)′>a/0.4 μm. More specifically in Example 1,it is when the effective F-number at the −2 stage is 9.0 upon stop-in(the 0 stage) that the effective F-number at the telephoto end meets theaforesaid formula. The then opening is 1C, so that any image degradationdue to diffraction phenomena by the stop is suppressed.

As shown, a turret 10′ of FIG. 28( a) may be used in place of the turretof FIG. 27. This turret 10′ is capable of making five-stage brightnessadjustments at 0, −1, −2, −3 and −4 stages, and located at an aperturestop position on the optical axis between the first lens group G1 andthe second lens group G2 forming part of the image pickup opticalsystem. The turret 10′ is provided with a 0-stage adjustment opening 1A′having a circular fixed aperture shape of about 4 mm in diameter, a −1stage correction opening 1B′ having an aperture area about half that ofthe opening 1A′ and a fixed aperture shape, and −2, −0.3 and −4 stagecorrection openings 1C′, 1D′ and 1E′ having a decreasing area in thisorder. The turret 10′ is rotated around its rotating shaft 11 to locateany one of the openings at the stop position for light quantityadjustments.

A plurality of such openings 1A′ to 1D′ are each provided with anoptical low-pass filter having different spatial frequencycharacteristics. As shown in FIG. 28( b), the arrangement is such thatthe smaller the aperture diameter, the higher the spatial frequencycharacteristics of the optical filter, thereby reducing any imagedegradation due to diffraction phenomena by stop-down. The respectivecurves in FIG. 28( b) show the spatial frequency characteristics of thelow-pass filters alone. In this regard, it is noted that thecharacteristics of the openings inclusive of diffractions by the stopsare all equally determined.

The electronic image pickup system constructed as described above may beapplied to phototaking systems where object images formed throughimage-formation optical systems such as zoom lenses are received atimage pickup devices such as CCDs or silver salt films, especially,digital cameras or video cameras as well as PCs and telephone sets whichare typical information processors, in particular, easy-to-carrycellular phones. Given below are some such embodiments.

FIGS. 29 to 31 are conceptual illustrations of a phototaking opticalsystem 41 for digital cameras, in which the image-formation opticalsystem of the invention is incorporated. FIG. 29 is a front perspectiveview of the outside shape of a digital camera 40, and FIG. 30 is a rearperspective view of the same. FIG. 31 is a sectional view of theconstruction of the digital camera 40. In this embodiment, the digitalcamera 40 comprises a phototaking optical system 41 including aphototaking optical path 42, a finder optical system 43 including afinder optical path 44, a shutter 45, a flash 46, a liquid crystalmonitor 47 and so on. As the shutter 45 mounted on the upper portion ofthe camera 40 is pressed down, phototaking takes place through thephototaking optical system 41, for instance, the optical path bendingzoom optical system according to Example 2. An object image formed bythe phototaking optical system 41 is formed on the image pickup plane ofa CCD 49 via a near-infrared cut filter IF and an optical low-passfilter. The object image received at CCD 49 is displayed as anelectronic image on the liquid crystal monitor 47 via processing means51, which monitor is mounted on the back of the camera. This processingmeans 51 is connected with recording means 52 in which the phototakenelectronic image may be recorded. It is here noted that the recordingmeans 52 may be provided separately from the processing means 51 or,alternatively, it may be constructed in such a way that images areelectronically recorded and written therein by means of floppy discs,memory cards, MOs or the like. This camera may also be constructed inthe form of a silver salt camera using a silver salt camera in place ofCCD 49.

Moreover, a finder objective optical system 53 is located on the finderoptical path 44. An object image formed by the finder objective opticalpath 53 is in turn formed on the field frame 57 of a Porro prism 55 thatis an image erecting member. In the rear of the Porro prism 55 there islocated an eyepiece optical system 59 for guiding an erected image intothe eyeball E of an observer. It is here noted that cover members 50 areprovided on the entrance sides of the phototaking optical system 41 andfinder objective optical system 53 as well as on the exit side of theeyepiece optical system 59.

With the thus constructed digital camera 40, it is possible to achievehigh performance and cost reductions, because the phototaking opticalsystem 41 is constructed of a fast zoom lens having a high zoom ratio atthe wide-angle end with satisfactory aberrations and a back focus largeenough to receive a filter, etc. therein.

In the embodiment of FIG. 31, plane-parallel plates are used as thecover members 50; however, it is acceptable to use powered lenses.

FIGS. 32 to 34 illustrates a personal computer that is one embodiment ofinformation processors in which the image-formation optical system ofthe invention is built in the form of an objective optical system. FIG.32 is a front perspective view of a personal computer or PC 300 in anuncovered state, FIG. 34 is a sectional view of a phototaking opticalsystem 303 in PC 300, and FIG. 34 is a side view of FIG. 32. As shown inFIGS. 32 to 34, PC 300 comprises a keyboard 301 for allowing an operatorto enter information therein from outside, information processing andrecording means (not illustrated), a monitor 302 for displaying theinformation to the operator, and a phototaking optical system 303 forphotataking an image of the operator per se and nearby images. Themonitor 302 used herein may be a transmission type liquid crystaldisplay illuminated from its back side by means of a backlight (notshown), a reflection type liquid crystal display designed to reflectlight from its front side for display purposes, a CRT display or thelike. As shown, the phototaking optical system 303 is built in the rightupper portion of the monitor 302; however, it may be located at anydesired position, for instance, around the monitor 302 or the keyboard301.

This phototaking optical system 303 comprises an objective lens 112mounted on a phototaking optical path 304 and formed of the opticalpath-bending zoom optical system of the invention (roughly shown) and animage pickup chip 162 for receiving images, which are built in PC 300.

In this embodiment, a low-pass filter LF is additionally applied ontothe image pickup chip 162 to form a one-piece unit 160 that can bemounted at the rear end of the lens barrel 113 of the objective lens 112in one-touch snap operation. Thus, any centering or inter-surfaceadjustment for the objective lens 112 and image pickup chip 162 can bedispensed with, and so smooth assembly is achieved. Further, the lensbarrel 113 is provided at the other end with a cover glass 114 forprotection of the objective lens 112. It is here noted that the zoomlens drive mechanism in the lens barrel 113 is not shown.

An object image received at the image pickup chip 162 is entered intothe processing means of PC 300 via a terminal 166 and displayed as anelectronic image on the monitor 302. As an example, an image 305phototaken of the operator is shown in FIG. 32. The image 305 may bedisplayed on a personal computer on the other end of the line by way ofprocessing means and the Internet or a telephone.

FIG. 35 is illustrative of a telephone set, especially aconvenient-to-carry cellular phone that is one exemplary informationprocessor in which the image-formation optical system of the inventionis built as a phototaking optical system. FIGS. 35( a) and 35(b) are afront view and a side view of a cellular phone 400, and FIG. 35( c) is asectional view of a phototaking optical system 405. As shown in FIGS.35( a) to 35(c), the cellular phone 400 comprises a microphone 401through which the voice of an operator is entered as information, aspeaker 402 through which the voice of a person on the other end of thelike is produced, an input dial 403 through which the information isentered by the operator, a monitor 404 for displaying images phototakenof the operator per se, the person on the other end of the line and soon as well as information such as telephone numbers, a phototakingoptical system 405, an antenna 406 for transmission and reception ofradio waves for communications, and processing means (not shown) forprocessing image information, communications information, input signals,etc. Here a liquid crystal display is used for the monitor 404. How therespective devices are arranged is not particularly limited to thearrangement shown in FIG. 41. This phototaking optical system 405comprises an objective lens 112 mounted on a phototaking optical path407 and formed of the optical path-bending zoom optical system of theinvention (roughly shown) and an image pickup chip 162 for receivingobject images, which are built in the cellular phone 400.

In this embodiment, a low-pass filter LF is additionally applied ontothe image pickup chip 162 to form a one-piece unit 160 that can bemounted at the rear end of the lens-barrel 113 of the objective lens 112in one-touch snap operation. Thus, any centering or inter-surfaceadjustment for the objective lens 112 and image pickup chip 162 can bedispensed with, and so smooth assembly is achieved. Further, the lensbarrel 113 is provided at the other end (not shown) with a cover glass114 for protection of the objective lens 112. It is here noted that thezoom lens drive mechanism in the lens barrel 113, etc. are not shown.

An object image received at the image pickup chip 162 is entered intoprocessing means (not shown) via a terminal 166, so that the image isdisplayed as an electronic image on the monitor 404 and/or a monitor onthe other end of the line. To transmit the image to the person on theother end, the signal processing means has a signal processing functionof converting information on the object image received at the imagepickup chip 162 to transmittable signals.

As can be appreciated from the foregoing explanation, the presentinvention can provide a zoom lens that is received in a lens mount withsmaller thickness and efficiency, has high magnifications and isexcellent in image-formation capability even on rear focusing, andenables video cameras or digital cameras to be thoroughly slimmed down.

1. An electronic image pickup apparatus, comprising a zoom opticalsystem comprising: a reflecting optical element for bending an opticalpath, a lens located on an object side with respect to said reflectingoptical element, and a lens group that is located on an image side withrespect to said reflecting optical element and movable during zooming,and an electronic image pickup device located on an image side of saidzoom optical system; wherein said reflecting optical element isrelocated to receive in the resulting space said lens that is located onan object side with respect to said reflecting optical device.
 2. Theelectronic image pickup apparatus according to claim 1, wherein saidreflecting optical element is a prism.
 3. The electronic image pickupapparatus according to claim 1, wherein when said reflecting opticalelement is relocated to receive in the resulting space said lens that islocated on an object side with respect to said reflecting opticalelement, said lens group that is located on an image side with respectto said reflecting optical element and movable during zooming isrelocated toward the image side.
 4. The electronic image pickupapparatus according to claim 1, wherein said lens to be received is anegative lens.